Next, a chemical reaction of interest was conducted in the same constant volume calorimeter. The neutralization reaction of HCl(aq) with NaOH(aq) caused the temperature of the calorimeter to rise by 2.46 °C. What is the change in internal energy ΔU of the neutralization reaction in kJ?
Answer:
A constant volume calorimeter (bomb calorimeter) was calibrated by performing in it a reaction in which 5.23 kJ of heat energy was released, causing the calorimeter to rise by 7.33 °C. What is the heat capacity Cy of the calorimeter
Explanation:
the heat capacity of the calorimeter is
[tex]C_v = \frac{q}{\Delta T} \\\\=\frac{5.23}{7.33} \\\\=0.714kJ /^\circ C[/tex]
Now that our heat capacity of the calorimeter is 0.714kJ/°C
we can easily calculate the change in internal energy ΔU of the neutralization reaction
[tex]\Delta U = C_v \ dt[/tex]
or
[tex]\Delta U = C_V \Delta T[/tex]
Δ T = 2.46 °C
[tex]C_v = 0.714 kJ/ ^\circ C[/tex]
[tex]\Delta U = 0.714*2.46\\\\=1.7564kJ[/tex]
A sample tube consisted of atomic hydrogen in their ground state. A student illuminated the atoms with monochromatic light, that is, light of a single wavelength. If only two separate emission lines in the visible region are observed, what is the wavelength (or wavelengths) of the incident radiation?
Answer:
The wavelength of the monochromatic light is 486.2 nm.
Explanation:
The illumination of the hydrogen atom by the monochromatic light causes an absorption of energy by its electrons which causes an excitation. After a period, the particle de-excites (decays) losing the absorbed energy and falls back to its initial state releasing the energy in the form of a photon. This photon can be observed as a colored light of the Balmer series.
From Rydberg's expression,
1/λ=−R([tex]\frac{1}{n_{2} ^{2} }[/tex] − [tex]\frac{1}{n_{1} ^{2} }[/tex])
The transition of the electron is from n = 2 to 4, so that;
1/λ = R ([tex]\frac{1}{2^{2} }[/tex] - [tex]\frac{1}{4^{2} }[/tex])
= 1.097 x [tex]10^{7}[/tex] ([tex]\frac{1}{2^{2} }[/tex] - [tex]\frac{1}{4^{2} }[/tex])
1/λ = 2056875
So that,
λ = [tex]\frac{1}{2056875}[/tex]
= 4.8617 x [tex]10^{-7}[/tex] m
The wavelength of the monochromatic light is 486.2 nm.
A technician prepared a solution by heating 100 milliliters of distilled water while adding KCl crystals until no more KCl would dissolve. She then capped the clear solution and set it aside on the lab bench. After several hours she noticed the solution had become cloudy and some solid had settled to the bottom of the flask. Which statement best describes what happened?
A. As the solution cooled, evaporation of water increased the KCl concentration beyond its solubility
B. Water molecules, trapped with the KCl crystals, were released after heating
C. At lower temperatures the solubility of the KCl decreased and recrystallization occurred
D. At increased temperatures the solubility of KCl increased and remained too high after cooling
Answer:
At lower temperatures the solubility of the KCl decreased and recrystallization occurred
Explanation:
Solubility refers to the amount of solute that dissolves in one litre of water at a particular temperature. Solubility is a property referring to the ability for a given substance, the solute, to dissolve in a solvent. It is measured in terms of the maximum amount of solute dissolved in a solvent at equilibrium. The resulting solution is called a saturated solution.
Solubility is dependent on temperature. This is the reason why we must state the particular temperature at which a given solubility data was collected. Above or below the quoted temperature, the solubility data may no longer be accurate.
Let's return to the question, at elevated temperatures, we can see that the KCl is very soluble in water as evidenced by the clear solution obtained at high temperature. However, as the temperature decreases, the solubility of KCl also decreases accordingly and recrystallization of the solute occurred hence the formation of a cloudy solution and the settling of some solid at the bottom of the flask.
Answer:
C. At lower temperatures the solubility of the KCl decreased and recrystallization occurred
Explanation:
Match the term to its description.
Gravitational energy
Answer 1
Mechanical energy
Answer 2
Nuclear energy
Answer 3
Thermal energy
Answer 4
Internal energy caused by vibrations of atoms and molecules
The potential energy of position
The energy of an object due to its movement
Energy stored in the nucleus of an atom
Answer:
Gravitational Energy: The energy of an object due to its movement
Mechanical Energy: The potential energy of position
Nuclear Energy: internal energy caused by vibrations of atoms and molecules
Thermal Energy: Energy stored in the nucleus of an atom
Answer:
radiant
nuclear
thermal
potential
Explanation:
In an ionic compound, the size of the ions affects the internuclear distance (the distance between the centers of adjacent ions), which affects lattice energy (a measure of the attractive force holding those ions together). Based on ion sizes, arrange these compounds by their expected lattice energy. Note that many sources define lattice energies as negative values. Please arrange by magnitude and ignore the sign.
Compunds: RbCl ,RbBr ,Rbl ,RbF
Answer:
The correct answer will be " RbF > RbCl > RbBr > Rbl".
Explanation:
The size of the given ions will be:
RbCl:
⇒ 689kJ/mol
RbBr:
⇒ 660kJ/mol
Rbl:
⇒ 630kJ/mol
RbF:
⇒ 785kJ/mol
Now according to the size, the arrangement will be:
⇒ (785kJ/mol) > (689kJ/mol) > (660kJ/mol) >(630kJ/mol)
⇒ RbF > RbCl > RbBr > Rbl
The bond among all opposite charging ions seems to be strongest whenever the ions were indeed small.
Since density depends on the mass and volume of an object, we need both of these values combined in the correct way to solve for density. Keep in mind that we may not be given the mass and volume directly, or the values may not be given in the units we want and we need to convert to the correct units before solving for density.When converting between metric units, use the prefixes to help you determine the magnitude of a value. The prefix k indicates kilo, 1000. Therefore 1000 g = 1 kg.A 11.0 kg iron weightlifting plate has a volume of 1400 cm3 . What is the density of the iron plate in g/cm3?Express your answer in grams per cubic centimeter to three significant figures.
Answer:
7.86 g/cm³
Explanation:
11.0 kg = 11,000 g
The density in g/cm³ is ...
(11,000 g)/(1,400 cm³) = 7.86 g/cm³
express your answer to three significant figures and include appropriate units
Answer:
58.702
Explanation:
Data obtained from the question include:
Mass number of isotope 1 (M1) = 57.93
Abundance of isotope 1 (M1%) = 67.76%
Mass number of isotope 2 (M2) = 59.93
Abundance of isotope 2 (M2%) = 26.16%
Mass number of isotope 3 (M3) = 60.93
Abundance of isotope 3 (M3%) = 1.25%
Mass number of isotope 4 (M4) = 61.93
Abundance of isotope 4 (M4%) = 3.66%
Mass number of isotope 5 (M5) = 63.93
Abundance of isotope 5 (M5%) = 1.16%
Relative atomic mass =...?
The relative atomic mass(RAM) of the element can be obtained by doing the following:
RAM = [(M1×M1%) /100] +[(M2×M2%) /100] + [(M3×M3%) /100] + [(M4×M4%) /100] + [(M5×M5%) /100]
RAM = [(57.93×67.76)/100] + [(59.93×26.16)/100] + [(60.93×1.25) /100] + [(61.93×3.66)/100] + [(63.93×1.16)/100]
RAM = 39.253 + 15.678 + 0.762 + 2.267 + 0.742
RAM = 58.702
Therefore, the relative atomic mass (RAM) of the element is 58.702
Write a chemical formula for each molecular model. (Blue ball represents nitrogen atom, red ball represents oxygen atom, white ball represents hydrogen atom, black ball represents carbon atom, yellow ball represents sulphur atom.)
Answer:
See answer below
Explanation:
In this case, you are missing the picture. Luckily I found one on another site, so I hope is the one you are asking for. If not, please post again with the picture.
According to the picture below, you need to write a chemical formula for each molecular model.
To do this, is just simple. Let's see each model per separate.
In the first model, we have a blue ball and three white balls. According to the nomenclature of the question a blue ball represents nitrogen atoms and white ball represents hydrogen, therefore, we have an atom of nitrogen bonded to three atoms of hydrogens, so, the chemical formula should be:
NH₃: This molecule corresponds to the Ammonia molecule.
The second picture, shows 4 black balls (representing an atom of carbon each) and each black ball holds a determinated number of white balls. The two of the middle have two white balls each, and the terminals have 3 white balls, therefore, the molecule should be the following:
CH₃ - CH₂ - CH₂ - CH₃: this corresponds to the butane
Finally, the last picture shows a yellow ball (which represents sulphur) and three red balls (representing oxygen each), so, the molecule that represents this would be:
SO₃: this is the sulfite ion.
How do I calculate the moles consumed in a vinegar titration?
Answer: Use the titration formula
Explanation:
What are the differences between HDL and LDL?
Answer:
LDL is
low density lipid
HDL is
high density lipid
Explanation:
HDL helps rid your body is excess cholesterol so so it won't end up in your arteries
LDL is also called "bad cholesterol" because it takes cholesterol to your arteries
The volume measuring system for a gasoline pump at the service station is calibrated at 20.0°C. If the temperature of the gasoline drops to 10.0°C, what percentage extra amount of mass of gasoline do you receive when making a purchase? The coefficient of volume expansion for gasoline is 9.5 × 10-4/K.
Answer:
answer = -0.95
Explanation:
Need help with these 7 problems
Answer:
1. 2.3
2. 4.5
3. 10.5
4. 5.6
5. 3.5
6. 3.9
7. 1.6
Explanation:
pH = - log [H+]
1. Lemon juice
[H+] = 0.005
pH = - log [H+]
pH = - log 0.005
pH = 2.3
2. Beer
[H+] = 3.16x10^-5
pH = - log [H+]
pH = - log 3.16x10^-5
pH = 4.5
3. Milk of Magnesia
[H+] = 3.16x10^-11
pH = - log [H+]
pH = - log 3.16x10^-11
pH = 10.5
4. Rain water
[H+] = 2.51x10^-6
pH = - log [H+]
pH = - log 2.51x10^-6
pH = 5.6
5. Soda
[H+] = 3.16x10^-4
pH = - log [H+]
pH = - log 3.16x10^-4
pH = 3.5
6. Tomatoes
[H+] = 1.23x10^-4M
pH = - log [H+]
pH = - log 1.23x10^-4
pH = 3.9
7. Bleach
[OH-] = 2.3x10^-2M
pOH = - log [OH-]
pOH = - log 2.3x10^-2
pOH = 1.6
What is the concentration of a 34% solution converted to parts per million (ppm).?
34,000,000 ppm
340.000 ppm
34,000 ppm
3,400 ppm
Answer:
340.000 ppm
Explanation:
Parts per million (ppm) is a unit of measure for concentration that measures the number of units of substance per million units of the set. It is a concept homologous to the percentage, only in this case it is not parts per percent but per million. The ppm calculation method is different for solids, liquids and gase. There are many formulas, however in this case, you can use this fact:
[tex]10000ppm=1\%[/tex]
Using Cross-multiplication:
[tex]\frac{10000ppm}{x} =\frac{1\%}{34\%}[/tex]
Solving for [tex]x[/tex] :
[tex]x=34*10000=340000ppm[/tex]
Therefore, the concentration of a 34% solution converted to parts per million is:
[tex]340000ppm[/tex]
Determine the value of the equilibrium constant, Kgoal, for the reaction N2(g)+H2O(g)⇌NO(g)+12N2H4(g), Kgoal=? by making use of the following information: 1. N2(g)+O2(g)⇌2NO(g), K1 = 4.10×10−31 2. N2(g)+2H2(g)⇌N2H4(g), K2 = 7.40×10−26 3. 2H2O(g)⇌2H2(g)+O2(g), K3 = 1.06×10−10 Express your answer numerically.
Answer:
K = 1.79x10⁻³³
Explanation:
Using Hess's law, it is possible to fin K of a reaction by the algebraic sum of another related reactions.
In the reactions:
1. N2(g)+O2(g) ⇌ 2NO(g), K1 = 4.10×10−31 2.
2. N2(g)+2H2(g) ⇌ N2H4(g), K2 = 7.40×10−26
3. 2H2O(g)⇌2H2(g)+O2(g), K3 = 1.06×10−10
The sum of 1/2 (1) + 1/2 (2) produce:
N2(g) + 1/2O2(g) + H2(g) ⇌ 1/2N2H4(g) + NO(g)
And K' = √4.1x10⁻³¹×√7.4x10⁻²⁶ = 1.74x10⁻²⁸
Now, this reaction + 1/2 (3):
N2(g) + H2O(g) ⇌ NO(g) + 1/2N2H4(g)
And K of reaction is:
1.74x10⁻²⁸×√1.06x10⁻¹⁰ = 1.79x10⁻³³
Give 2 examples of a strong electrolyte
Answer:
Sodium Chloride, Potassium Chloride
Explanation:
Sodium Chloride, Potassium Chloride, are the most common example of a strong electrolyte. Most salts are strong electrolytes, such as hydrochloric acid, nitric acid, perchloric acid and sulphuric acid. Strong bases, such as sodium hydroxide and calcium hydroxide, are also potent electrolytes.
hope this helped!
A reaction is at equilibrium when...
A. the amounts of the reactants and products are not longer changing.
B. the reactants have all turned into products.
C. the products have all turned into reactants.
D. the amounts of the reactants and products are equal.
Answer:
Option A. is correct
Explanation:
A reaction is at equilibrium when the amounts of the reactants and products are no longer changing.
Chemical equilibrium means that the rate of formation of products is equal to the rate at which the products re-form reactants.
Products are formed by the forward reaction and by the reverse reaction, the products re-form reactants.
Compare a 3s orbital to a 3p orbital. Which of the following are true? I. The orbitals have the same shape. II. The orbitals have different shapes. III. The orbitals have the same energy. IV. The orbitals have different energies.
Answer:
II. The orbitals have different shapes.
IV. The orbitals have different energies.
Explanation:
1. Shapes
Below are pictures of a 3s and a 3p orbital.
The 3s orbital has a spherical shape, and the 3p orbital has a dumbbell shape.
2. Energies
For every element except H, the order of energies is
3s < 3p
For a hydrogen atom,
3s = 3p
Consider the reaction below. 2C6H14 + 19O2 Right arrow. 12CO2 + 14H2O How many moles of hexane (C6H14) must burn to form 18.4 mol of carbon dioxide?
Answer:
[tex]3.06mol~C_6H_14[/tex]
Explanation:
We have to start with the reaction:
[tex]2C_6H_1_4 + 19O_2->12CO_2 + 14H_2O[/tex]
We have 2 carbons, 6 hydrogens and 38 oxygens on both sides.
Now the molar ratio between [tex]C_6H_14[/tex] and [tex]CO_2[/tex] is 2:12 or [tex]2~mol~C_6H_14=~12~mol~CO_2[/tex]. With this in mind we can calculate the moles of [tex]C_6H_14[/tex], so:
[tex]18.4~mol~CO_2\frac{2~mol~C_6H_14}{12~mol~CO_2}=3.06mol~C_6H_14[/tex]
I hope it helps!
Answer:
B) 3.07 mol
Explanation:
Using the relationship given in part 1, calculate Ecell if [Cu2+] = 1.453 M and [Cr3+] = 0.00176 M, assuming that the temperature remains at 25°C. Give your answer to two places after the decimal.
Answer:
1.05 V
Explanation:
Now recall Nernst equation;
Ecell= E°cell - 0.0592/n log [Red]/[Ox]
Now we look at the values of E°cathode and E°anode
E°cathode= 0.34 V
E°anode = -0.74 V
E°cell= 0.34-(-0.74)
E°cell= 1.08 V
[Red] = 1.453 M
[Ox] = 0.00176 M
n= 6
Ecell= E°cell - 0.0592/n log [Red]/[Ox]
Ecell= 1.08 - 0.0592/6 × log[1.453]/[0.00176]
Ecell= 1.08 - 0.0592/6 × 2.917
Ecell= 1.08 - 0.02878
Ecell= 1.05 V
A sample tube consisted of atomic hydrogen in their ground state. A student illuminated the atoms with monochromatic light, that is, light of a single wavelength. If only two separate emission lines in the visible region are observed, what is the wavelength (or wavelengths) of the incident radiation?
Answer:
The wavelength is [tex]\lambda =97.3 nm[/tex]
Explanation:
Generally the series whose emission line show on the visible spectrum is the
Balmar series so this two emission line seen on the visible spectrum could either be due to the move of electron from
[tex]n=3 \to \ n=2[/tex]
OR
[tex]n=4 \to n=2[/tex]
This implies that the first excitement is from [tex]n_i=1 \to \ n_f=4[/tex]
So the energy change due to the excitement is mathematically represented as
[tex]\Delta E = R_H [\frac{1}{n_i^2} -\frac{1}{n_f^2} ][/tex]
substituting values
[tex]\Delta E= R_H [\frac{1}{1^2} -\frac{1}{4^2} ][/tex]
[tex]\Delta E= \frac{15}{16} R_H[/tex]
This energy change can also be represented as
[tex]\Delta E = \frac{hc}{\lambda}[/tex]
So [tex]\frac{15}{16} R_H = \frac{hc}{\lambda}[/tex]
=> [tex]\lambda = \frac{16hc}{15 R_H}[/tex]
Where [tex]R_H[/tex] is the Rydberg constant with a value of [tex]R_H = 2.18 * 10^{-18} J.[/tex]
h is the Planck's constant with values [tex]h = 6.626 * 10^{-34} m^2 kg / s[/tex]
c is the speed of light with value [tex]c = 3.0*10^{8} \ m/s[/tex]
So
[tex]\lambda = \frac{16(6.626 *10^{-34})(3*10^{8})}{15 * (2.18*10^{-18})}[/tex]
[tex]\lambda = 9.73 *10^{-8} \ m[/tex]
[tex]\lambda =97.3 nm[/tex]
Under certain conditions the rate of this reaction is zero order in ammonia with a rate constant of 0.0089 M.s^-1:
2NH3(g) → N2(g)+ 3H2(g)
Suppose a 5.0 L flask is charged under these conditions with 400. mmol of ammonia. How much is left 2.0 s later? You may assume no other reaction is important.
Be sure your answer has a unit symbol, if necessary, and round it to 2 significant digits.
Answer:
Explanation:
The rate of reaction will not depend upon concentration of reactant . It will be always constant and equal to .0089M s⁻¹.
Initial moles of reactant = 400 x 10⁻³ mole in 5 L
molarity = 400 x 10⁻³ /5 M
= 80 x 10⁻³ M .
= .08M
no of moles reacted in 2 s = .0089 x 2
= .0178 M
concentration left = .08 - .0178 M
= .0622 M .
No of moles left in 5 L
= 5 x .0622 = .31 moles .
Be sure to answer all parts. Give the name and the formula of the compound formed from the following elements: (a) bromine and rubidium Name: (select) (select) Formula: (b) strontium and sulfur Name: (select) (select) Formula: (c) barium and chlorine Name: (select) (select) Formula
Answer:
These are the chemical names and molecular formula of the compounds formed from these elements:
Rubidium + Bromine = Rubidium bromide, RbBrStrontium + Sulphur = Strontium sulfide, SrSBarium and Chlorine = Barium chloride, [tex]BaCl_{2}[/tex]For the general reaction aA + bB cC + DD, has the general rate law, rate k[A] [B].". What is the
correct algebraic equation for determining the units of the rate constant, k, when concentration is in M
and time is in seconds.
O
M
M's
k=
k=
MX+y.s
M*+y
O
Ma+b
O
M:s
k=
k
s
MX+y
O
M
o
S
k=
k=
Ma+b.s
M
O
M*+y
k=
S
Answer:
K=CHANGE IN CONCENTRATION/TIME TAKEN
Explanation:
Citric acid is one component of some soft drinks. Suppose that 8 L of solution are made from 0.24 g of citric acid, C6H8O7. What is the molarity of citric acid in the solution?
Answer:
The correct answer is 0.15 × 10⁻³ M.
Explanation:
C₆H₈O₇ is the molecular formula of citric acid. The mass of the one mole of the substance that comprise Avogadro's no of molecules is termed as the molar mass of the substance.
The molar mass of the citric acid (C₆H₈O₇) will be,
6 × atomic mass of carbon + 8 × atomic mass of hydrogen + 7 × atomic mass of oxygen = 6×12 + 8×1 + 7×16 = 192. Thus, the molar mass of citric acid is 192 g/mol.
The value of the solution given in the question is 8 L.
The mass of citric acid given is 0.24 g or 240 mg, which can also be written as 240/1000 g or 240 × 10⁻³ g.
The number of moles can be calculated by using the formula = mass / molar mass. Thus, by putting the values we get,
= 240 × 10⁻³ g / 192 g/mol
= 1.25 × 10⁻³ mol
The number of moles of the solute present in the 1 liter of the solution is termed as the molarity of the solution. The formula of molarity or M is,
= no of moles of solute / volume of solution in L
Now putting the values we get,
= 1.25 × 10⁻³ mol / 8 L
= 0.156 × 10⁻³ M
Hence, the molarity of citric acid in the given solution is 0.15 × 10⁻³ M
50 mL of CH3CH2Br (bromoethane) and 50 mL of water are poured into a separatory funnel. Bromoethane is a water‑insoluble compound with a density of 1.460gmL . The funnel is stoppered and the mixture is shaken vigorously. After standing, two layers separate. Which substance is in which layer? Explain. Bromoethane is more dense than water. Water is added second. The top layer is bromoethane and the bottom layer is water. The top layer is water and the bottom layer is bromoethane. Bromoethane has a higher molar mass than does water. b) Into the same funnel is poured carefully 50 mL of hexane (density = 0.660 g/mL) so that the other two layers are not disturbed. The hexane forms a third layer. The funnel is stoppered, and the mixture is shaken vigorously. After standing, two layers separate. Which compound(s) are in which layer? The top layer contains: The bottom layer contains:
Answer:
See explanation below
Explanation:
In this case, we can explain this in a very basic way.
We know that heavier objects will go always at the bottom when we are carrying two objects, one heavier than the other right?
In the same manner works the density of two liquids. In this case, we have a mix of water and bromoethane. Bromoethane is an organic compound and it's less polar than water which is extremely polar. When we mix these two liquids, we can see that both of them are insoluble, so no matter how much we shake the funnel, the liquids will not mix to form a solution.
Instead of that, both of them will be in the funnel, and they'll be gradually separating into two layers. The bromoethane has a higher density than water, this means that in the bottom layer we will have the bromoethane and in the top layer we will have the water.
In case you are wondering what happens if we added water first and then, the bromoethane?, it will happen the same, it does not matter the order you add the liquid, because density here is a very important factor, so when the water is added no matter which position, it will go to the top layer after the bromoethane is added.
Now when the hexane is added, it will form now three layers, and again, density plays an important factor. The higher density will go to the bottom, and the lowest to the top.
In this case, the order of layer will be:
Top layer: hexane (d = 0.66 g/mL)
Middle layer: water (d = 1 g/mL)
Bottom layer: bromoethane (d = 1.46 g/mL)
Hope this helps
Draw the structure of the bromohydrin formed when (Z)-3-hexene reacts with Br2/H2O. Use the wedge/hash bond tools to indicate stereochemistry where it exists. If the reaction produces a racemic mixture, draw both stereoisomers. Separate multiple products using the sign from the drop-down menu.
Answer:
(3R,4R)-4-bromohexan-3-ol
Explanation:
In this case, we have reaction called halohydrin formation. This is a markovnikov reaction with anti configuration. Therefore the halogen in this case "Br" and the "OH" must have different configurations. Additionally, in this molecule both carbons have the same substitution, so the "OH" can go in any carbon.
Finally, in the product we will have chiral carbons, so we have to find the absolute configuration for each carbon. On carbon 3 we will have an "R" configuration on carbon 4 we will have also an "R" configuration. (See figure 1)
I hope it helps!
Polymers are large molecules composed of simple units repeated many times. Thus, they often have relatively simple empirical formulas. Calculate the empirical formulas of the polyethylene: 86% C, 14% H. You must show all work for credit. Polymers are large molecules composed of simple units repeated many times. Thus, they often have relatively simple empirical formulas. Calculate the empirical formulas of the polystyrene: 92.3% C, 7.7% H. You must show all work for credit.
Answer:
A. CH2.
B. CH.
Explanation:
A. Determination of the empirical formula of polyethylene.
Data obtained from the question include:
Carbon (C) = 86%
Hydrogen (H) = 14%
The empirical formula of the polyethylene can be obtained as follow:
C = 86%
H = 14%
Divide by their molar mass
C = 86/12 = 7.17
H = 14/1 = 14
Divide by the smallest
C = 7.17/7.17 = 1
H = 14/7.17 = 2
Therefore, the empirical formula of the polyethylene is CH2.
B. Determination of the empirical formula of polystyrene
Data obtained from the question include:
Carbon (C) = 92.3%
Hydrogen (H) = 7.7%
The empirical formula of the polystyrene can be obtained as follow:
C = 92.3%
H = 7.7%
Divide by their molar mass
C = 92.3/12 = 7.69
H = 7.7/1 = 7.7
Divide by the smallest
C = 7.69/7.69 = 1
H = 7.7/7.69 =
Therefore, the empirical formula of the polystyrene is CH.
The electron in a hydrogen atom, originally in level n = 8, undergoes a transition to a lower level by emitting a photon of wavelength 3745 nm. What is the final level of the electron? (c = 3.00 x 108m/s, h = 6.63 x 10−34 J • s, RH = 2.179 x 10−18 J)
a. 5
b. 6
c. 8
d. 9
e. 1
Answer:
The level is [tex]n_1 = 5[/tex]
Explanation:
From the question we are told that
The level of the hydrogen atom is [tex]n_2 = 8[/tex]
The wavelength of the photon is [tex]\lambda = 3745 nm = 3745 *10^{-9} \ m[/tex]
Generally the wave number is mathematically represented as
[tex]k = \frac{1}{\lambda }[/tex]
Now this wave number can also be mathematically represented as
[tex]k = R_{\infty} [\frac{1}{n_1^2} + \frac{1}{n_2^2} ][/tex]
This implies that
So
Here [tex]R_{\infty}[/tex] is the Rydberg constant, with a value [tex]1.097 * 10^7[/tex]
and [tex]n_1 \ and \ n_2[/tex] are the principal quantum levels
substituting values
[tex]0.0243= [\frac{1}{n_1^2} - \frac{1}{8^2} ][/tex]
[tex]0.0243= \frac{1}{n_1^2} - 0.015625[/tex]
[tex]0.0243 + 0.015625= \frac{1}{n_1^2}[/tex]
[tex]n_1 = 5[/tex]
in what type of reaction or process does heat flow into the system
Answer: The correct answer is: " endothermic . "
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Note: Heat flows into [heat may be absorbed within] an "endothermic" reaction or system
To the contrary, heat flows out [heat may exit from or may be released from] an "exothermic" reaction or process.
Hint: Think of the "prefixes" of: "endothermic" and "exothermic" :
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1) endo- = "within" (as in "endothermic" —heat tends to be absorbed/"within"/"released within"/released within"/into" ;
2) exo- = " outwards"/"exit" (as in "exothermic") —heat tends to '"exit"/leave/escape from/"be released out of/form".
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Hope this is helpful to you!
Best wishes to you in your academic pursuits
—and within the "Brainly" community"!
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Analyses of enzymes found in the blood are used as indicators that tissue damage (heart, liver, muscle) has occurred and resulted in the leakage of cellular enzymes into the bloodstream. One of the common enzymes measured for this purpose is the one that interconverts lactate and pyruvate. Identify the name of this enzyme.
Answer:
Lactate dehydrogenase (LDH)
Explanation:
LDH is tetrameric enzyme found in the muscles (M-type) and the heart (H-type) of living cells, responsible for the conversion of pyruvate to lactate and back, to promote generation of nicotinamide adenine dinucleotide (NAD).
