Answer:
pH → 7.47
Explanation:
Caffeine is a sort of amine, which is a weak base. Then, this pH should be higher than 7.
Caffeine + H₂O ⇄ Caffeine⁺ + OH⁻ Kb
1 mol of caffeine in water can give hydroxides and protonated caffeine.
We convert the concentration from mg/L to M
415 mg = 0.415 g
0.415 g / 194.19 g/mol = 2.14×10⁻³ mol
[Caffeine] = 2.14×10⁻³ M
Let's calculate pH. As we don't have Kb, we can obtain it from pKb.
- log Kb = pKb → 10^-pKb = Kb
10⁻¹⁰'⁴ = 3.98×10⁻¹¹
We go to equilibrium:
Caffeine + H₂O ⇄ Caffeine⁺ + OH⁻ Kb
Initially we have 2.14×10⁻³ moles of caffeine, so, after the equilibrium we may have (2.14×10⁻³ - x)
X will be the amount of protonated caffeine and OH⁻
Caffeine + H₂O ⇄ Caffeine⁺ + OH⁻ Kb
(2.14×10⁻³ - x) x x
We make the expression for Kb:
3.98×10⁻¹¹ = x² / (2.14×10⁻³ - x)
We can missed the -x in denominator, because Kb it's a very small value.
So: 3.98×10⁻¹¹ = x² / 2.14×10⁻³
√(3.98×10⁻¹¹ . 2.14×10⁻³) = x → 2.92×10⁻⁷
That's the [OH⁻]. - log [OH⁻] = pOH
- log 2.92×10⁻⁷ = 6.53 → pOH
14 - pOH = pH → 14 - 6.53 = 7.47
Water (H2O) is a polar molecule. Ethane (C2H6) is nonpolar.
What is true about water and ethane?
Ethane is likely to have a higher boiling point because it is nonpolar.
Ethane is likely to have a higher boiling point because it has fewer atoms per molecule.
Water is likely to have a higher boiling point because it has fewer atoms per molecule.
Statement which is true about ethane and water is that water is likely to have a higher boiling point because it has fewer atoms per molecule.
What is an atom?An atom is defined as the smallest unit of matter which forms an element. Every form of matter whether solid,liquid , gas consists of atoms . Each atom has a nucleus which is composed of protons and neutrons and shells in which the electrons revolve.
The protons are positively charged and neutrons are neutral and hence the nucleus is positively charged. The electrons which revolve around the nucleus are negatively charged and hence the atom as a whole is neutral and stable due to presence of oppositely charged particles.
Atoms of the same element are similar as they have number of sub- atomic particles which on combination do not alter the chemical properties of the substances.
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A student adds 5400.0mL of 0.15M NaOH to 201.2mL of 4.0M NaOH. What is the final [NaOH]?
Answer:
0.287 M
Explanation:
Multiply the concentration of each solution by the volume of each (in liters) to get the moles of NaOH in that solution.
0.15 M • 5.4000 L = 0.81 mol NaOH
4.0 M • 0.2012 L = 0.80 mol NaOH
Add the mol of NaOH together to get the total --> 0.81 + 0.80 = 1.61 mol NaOH
Divide by the total volume of solution (5400.0 mL + 201.2 mL = 5,601.2 mL = 5.6012 L)
1.61 mol / 5.6012 L = 0.287 M NaOH
How does molecular shake affect polarity?
Answer:
I believe its A
Explanation:
A molecule that has a symmetrical shape will be a nonpolar molecule.
Iron(II) sulfide +
potassium—> makes what ?
Answer:
Potassium Sulfide
Explanation:
K is more reactive than Fe which means K displaces Fe from the equation
In test tube 3, 3 mL of .002 M Fe(III) solution is combined with 7 mL of .02 M 5-sulfosaliclic acid (SSA) solution. What is the mole fraction of SSA in the test tube
Answer:
0.96
Explanation:
Number of moles of Fe(III) = 3/1000 * 0.002 M = 6 * 10^-6 moles
Number of moles of SSA = 7/1000 * 0.02 = 1.4 * 10^-4 moles
Total number of moles = 6 * 10^-6 moles + 1.4 * 10^-4 moles
Mole fraction of SSA = number of moles of SSA/ total number of moles.
Mole fraction of SSA = 1.4 * 10^-4 moles/ 6 * 10^-6 moles + 1.4 * 10^-4 moles
Mole fraction of SSA = 0.96
A steel bottle contains nitrogen gas at STP. What is the final pressure if the temperature is changed to 155°C?
Answer:
Option D
Explanation:
As we know at
PV = nRT
at STP,
Pressure is 1 atm and temperature is 273 K
[tex]\frac{P_2}{P_1} = \frac{T_2}{T_1} \\P_2 = 1*(428 )/273\\P_2 = 1.567[/tex]
Hence, option D is correct
How many moles would there be in 500,000,000,000 atoms of silver? Show your calculation
and answer in unit
Answer:
Answer: 3.01 * 10^35
Explanation:
500,000,000,000 * 6.02 * 10^23
5. The pictures below show four kinds of seeds. Which seed has a structure that
allows it to be carried away by wind?
A Bean seed
B Watermelon seed
C Dandelion seed
D Acorn
Answer:
Dandelion seed
Explanation:
(I learnt it in camp)
Answer:
C Dandelion Seed
Explanation:
Dandelion Seed are light enough to be carried by the wind.
When the equation H202 + H2O + O2 is completely balanced, the SUM of all the coefficients will be
A.5
B. 8
C.3
D.4
1. Long strands of DNA that contain lots of genes
A. Allele
B. Inherited Trait
C. Gene
D. Chromosome
Answer: chromosome
Explanation: :)
Toma en cuenta los textos para responder estas interrogantes: ¿Consideramos que la aplicación de las medidas de seguridad depende de las características de tu entorno?
Answer:
Si.
Explicación:
Sí, la aplicación de medidas de seguridad depende de las características de su entorno porque el entorno nos brinda para elegir las medidas de seguridad. Existen diferentes instrumentos utilizados para la seguridad de diferentes entornos. Algunas medidas de seguridad se aplican en un entorno mientras que el otro se aplica a otro entorno. Por ejemplo, el vallado es una medida de seguridad que se puede aplicar en el terreno pero no en el agua o cualquier zona fangosa, por lo que podemos decir que las características físicas deciden qué medida de seguridad se debe instalar en el entorno.
Which of the following is NOT a compound?
Water
Ammonia
Gold
Salt
The gold is not the compound.
The information related to the compound is as follows
It is the substance that contains the same type of molecules having 2 or more elements. It includes water, ammonia, salt, methane, carbon dioxide etc.In this, the elements should be bonded together.Therefore we can say that gold is not the compound.
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What are the four organelles that process, transport, and stone materials?ANSWER QUICK PLZZ no website
⦁ Find the concentration of H+, OH-, PH and POH of 0.03 M of magnesium hydroxide which ionizes to the extent of only 1 /3 in aqueous solution.
Answer:
[tex]pH=12.3\\\\pOH=1.7\\[/tex]
[tex][H^+]=5x10^{-13}M[/tex]
[tex][OH^-]=0.02M[/tex]
Explanation:
Hello there!
In this case, according to the given ionization of magnesium hydroxide, it is possible for us to set up the following reaction:
[tex]Mg(OH)_2(s)\rightleftharpoons Mg^{2+}(aq)+2OH^-(aq)[/tex]
Thus, since the ionization occurs at an extent of 1/3, we can set up the following relationship:
[tex]\frac{1}{3} =\frac{x}{[Mg(OH)_2]}[/tex]
Thus, x for this problem is:
[tex]x=\frac{[Mg(OH)_2]}{3}=\frac{0.03M}{3}\\\\x= 0.01M[/tex]
Now, according to an ICE table, we have that:
[tex][OH^-]=2x=2*0.01M=0.02M[/tex]
Therefore, we can calculate the H^+, pH and pOH now:
[tex][H^+]=\frac{1x10^{-14}}{0.02}=5x10^{-13}M[/tex]
[tex]pH=-log(5x10^{-13})=12.3\\\\pOH=14-pH=14-12.3=1.7[/tex]
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Two containers, illustrated below, are filled with the same amount and the same kind of ideal gas.
Which statement correctly describes the relationship between the contents of the two containers?
Container 1 particles have higher average kinetic energy and higher temperature than Container 2 particles.
Container 1 particles have lower average kinetic energy and lower temperature than Container 2 particles.
Container 1 particles have lower average kinetic energy and lower temperature than Container 2 particles.
Container 1 particles have lower average kinetic energy and higher temperature than Container 2 particles.
Container 1 particles have lower average kinetic energy and higher temperature than Container 2 particles.
Container 1 and Container 2 particles have the same average kinetic energy and the same temperature.
Container 1 and Container 2 particles have the same average kinetic energy and the same temperature.
Answer:
Container 1 particles have lower average kinetic energy and higher temperature than Container 2 particles.
Explanation:
Kinetic energy is the speed of the particles in the bottle.
As you can see in the illustration below, the patricles in Picture 2 are moving faster than the ones in Picture 1.
The tempature of Container 1 is higher because all of the particles are sitting on top of one another. Not being able to move, their pressure builds up and creates heat.
2. Which of the following is/are TRUE regarding net ionic equations?
A. Net ionic equations show only the particles directly involved in the
chemical change.
B. Spectator ions are included in complete equations, but not in net ionic
equations.
C. lonic charges do not need to be balanced in a net ionic equation.
D. Combustion, combination, and decomposition reactions can be written as
net ionic equations.
A and B are true.
C and D are false.
Out of the given four statements, A and B are only correct.
Explanation:
In the complete equation of a chemical reaction, the complete symbols of reactants and products are written along with states of matter under conditions at which the reaction is taking place.In the net ionic equation of a chemical reaction, only those chemical species are written which directly participating in the chemical reaction.The mass and charge in the net ion equation must be balancedIt is used in neutralization reactions, redox reactions, double displacement reactions.So from this, we can conclude that out of the given four statements, A and B are only correct.
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350.0 ML of air is at 23.0°C what is the volume at 90.0°C
Answer:
V=0.430 Liters
Explanation:
First off you need to convert ml to l and celsius to kelvin, in order for them to be in the S.I.
So, 350.0mL is 0.350 L and 23.0 C is (273.15+23=) 296.15 K (you can ignore the 0.15)
From the equation pV=nRT, lets name this equation (1), we can tell that the number of moles, pressure, and R, stay the same. The only thing changing is the volume, and temperature.
With the information given, let's figure out the pressure. From equation (1) if we solve it for the pressure of the gas, p=nRT/V => p=nR*296.15/0.350 => p=846.15 *nR
Now, we have to figure out the volume of the gas at 90.0 C (363.15 K), and solve equation (1) for volume, using the pressure we previously found.
v=nRT/p => v=nR*363.15/846.15*nR => (the nR's from top and bottom go away) v=0.429 L
Since we used 273.15 for the conversion of celsius to Kelvin, we could round up the number to
V=0.430 Liters
how does the concept of polarity relate to bond formation and molecular shape?
Answer: heyyyooo
The bond polarity for each bond in a BH3 molecule is polar, due to the difference in electronegativities of the B and H atom. The molecular shape is trigonal planar, and the molecule is non-polar - because due to the symmetry of the molecule, the polarities cancel out.
Explanation:
hope this helps!
How are ball and sticks and space filling are similar ?
Answer:
Ball and stick models are three-dimensional models where atoms are represented by spheres of different colors and bonds are represented by sticks between the spheres. ... Space fill models are similar to ball and stick models in that they are three-dimensional models that represent atoms as colored spheres.
A sample of gas at 300k has a volume of 2 liters at what temperature will the volume decrease to 1 liter if the pressure is kept constant
Answer:PV=nRT ideal gas law
P presdure
V volume
n number of moles of gas
R gas constant
T temperature
Explanation: V=nRT/P
2liters=nR300k/P
divide by 2 for the equation
1liters=nR150k/P
with nR remaining constant
A model is simplified version of a more complex idea or system. It useful to help us understand something we can't actually see
A) true
B) false
Answer:
I feel like the answer is A) true
Explanation:
you create a model to help your audience understand your complex idea. There have been models made to represent ideas that we cannot see.
What is the pH of a solution that has [H+] of .0042M?
Answer:
pH = 2.4
Explanation:
pH is defined as the negative log of the hydronium concentration.
Thus, we can plug in the given hydronium concentration:
pH = -log[H⁺] = -log[0.0042] = 2.4 (two significant figures)
The pH of the solution is 2.4.
P.S: Although I referred to [H⁺] as hydronium concentration, it is more accurate to express it as [H₃O⁺], though they are interchangeable and means the same thing.
The student wants to test the conductivity of each solution. Prior to carrying out the investigation, the student needs to identify the variables being controlled and the variables being changed between the two solutions. Which identification of the variables is correct?
Options:
The volume of the solution and the concentration of the solution are being changed between the two solutions, but the number of solute particles is being held constant.
The number of solute particles and the concentration of the solution are being changed between the two solutions, but the volume is being held constant.
The number of solute particles is being changed between the two solutions, but the volume and concentration of the solution is being held constant.
The volume of the solution and the number of solute particles are being changed between the two solutions, but the concentration of the solution is being held constant.
Answer:b
Explanation: the particles will soon dissolve which means that the particles are changing but the volume is staying the same and the concentration is changing
The identification of the variables which is correct is that the number of solute particles is being changed between the two solutions, but the volume and concentration of the solution is being held constant.
What are variables?Variables are defined as any characteristics, number or quantity which can be measured . It can also be called as a data item . It is called as variable because they can vary and can have variety of values.
There are three types of variables 1) manipulated variable where in a condition is specified, 2) responding variable which is dependent on manipulated variable 3)controlled variable which do not change.
Example of manipulated variables are number of hours spent by a student studying , that of responding variable is result of a student and temperature is an example of controlled variable.
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It take 38.70cm³ of 1.90 NaO4 to neutralize 10.30cm³ of H2So4 in a battery. Calculate the molar concentration of H2So4
Answer:
The molar concentration of base Cb = 14.2777M
Explanation:
Volume of acid Va = 38.70cm^3,
Concentration of acid NaO4 C_a= 1.90M
Volume of Base Vb = 10.30cm^3
Also, Equation of the reaction
H2SO4 + 2NaOH = Na2SO4 + 2H2O
No of mole of acid Na = 1
No of mole of base Nb = 2
CaVa/CbVb = Na/Nb
Cb = CaVaNb/VbNa
Cb = 1.9×38.7×2/(10.30×1)
Therefore, Cb = 14.2777M
The molar concentration of base Cb = 14.2777M
how many daughter cells would be produced if 32 cells undergo meiosis
Answer:
The meiosis process can for up to 4 daughter cells
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What is the mass in grams of 3.75 × 10 21 atoms of Li?
Answer:
The mass
Explanation:
the mass grams of 3.75 × 10 21 atoms of Li is
40. 21 atom of Li
1. Three fluids are poured from a beaker onto a lab table. Fluid A hits the table in 10 seconds, fluid B in 12 seconds, fluid C in 4 seconds, and fluid D
in 15 seconds. Which fluid has the highest viscosity?
O a fluid A
O b. fluid B
O c. fluid c
O d. fluid D
Answer:
fluid D
Explanation:
Fluid D has the highest viscosity because it is more difficult for it to move which makes it hit the table at 15 seconds
while fluid C has the lowest Viscocity which makes it move easily and it hit the table fastest
if i want to make 14 moles of potassium chloride, how many grams of potassium do i need? Show all work. Make sure to include unit and substance
Answer:
The answer is 0.013413582325191. i assume you are converting between moles Potassium Chloride and gram. The molecular formula for Potassium Chloride is KCl. The SI base unit for amount of substance is the mole. 1 mole is equal to 1 moles Potassium Chloride, or 74.5513 grams.
Explanation:
