Answer: A) A theory is the best possible explanation based on all existing evidence
A law in physics and chemistry is a description of what is going on. For instance, newton's law of motion helps us find out an objects acceleration if we know its mass and the force applied. The theory of gravity on the other hand is the best guess we make as to why objects with mass are attracted to one another.
Theories change over time if new evidence is found that contradicts the old theory. Saying "a theory is more important than a law" is subjective, and I would argue that both are equally important in their own way.
The atomic theory a theory is the best possible explanation based on all existing evidence. The correct option is A.
What is a theory?The word theory renowned as to an untested hunch or one can say a guess with not having a supporting evidence.
A theory, has nearly the opposite implications for scientists. A theory is a well-supported explanation of an innate phenomenon that can encompass laws, hypotheses, along with facts.
Theories are developed to elaborate, predict, as well as comprehend phenomena, also to challenge and extend existing understanding within the constraints of critical boundary assumptions.
A theory does not become a scientific law as new or better evidence accumulates.
The theories are explanations, as well as laws are patterns located in large amounts of data that are frequently expressed as an equation. A theory will always be a theory in all aspect, and a law will always be a law.
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What is the amount of charge on a calcium ion if its neutral atom has lost two valence electrons?
A. 1+
B. 2+
C. 3+
D. 4+
Answer: B
Explanation: a calcium ion has a charge of +2 because it has 2 more protons than electrons giving it a positive charge instead of neutral or negative.
State the number of sig figs in each value:
1) 0.00004050
2) 54.7000
3) 1,000.09
4) 0.039
Answer:
Explanation:
Significant figure implies number of digits that are to be considered. Some rules are required to be considered when writing a given expression to an expected significant figures.
So that:
1) 0.00004050 is 4 significant figures
2) 54.7000 is 6 significant figures
3) 1,000.09 is 6 significant figures
4) 0.039 is 2 significant figures
empirical formula of N4H8O4
Answer:
NH₂O
Explanation:
Given compound:
N₄H₈O₄
Unknown:
The empirical formula of the compound = ?
Solution:
The empirical formula of a compound is its simplest formula. It expresses the composition of a the compound in the simplest whole ratio of atoms of the different elements present in the compound.
For the given compound:
N₄H₈O₄
Number of moles of N = 4
H = 8
O = 4
the highest common factor is 4 and we simply divide through by this number;
N = 1
H = 2
O = 1
So, the empirical formula of compound is NH₂O
Which statements best describe half lives of radioactive isotopes
Answer:
The half-life varies depending on the isotope.
Half-lives range from fractions of a second to billions of years.
The half-life of a particular isotope is constant.
Explanation:
Make sure you add the options
Use the Rydberg Equation to calculate the energy in Joules of the transition between n = 7 and n = 3 for the hydrogen atom. Find the frequency in Hz of this transition if the wavelength is 1000nm.
Answer:
The energy of each transition is approximately [tex]1.98\times 10^{-19}\; \rm J[/tex].
The frequency of photons released in such transitions is approximately [tex]3.00\times 10^{14}\; \rm Hz[/tex].
Explanation:
The Rydberg Equation gives the wavelength (in vacuum) of photons released when the electron of a hydrogen atom transitions from one main energy level to a lower one.
Let [tex]\lambda_\text{vac}[/tex] denote the wavelength of the photon released when measured in vacuum.Let [tex]R_\text{H}[/tex] denote the Rydberg constant for hydrogen. [tex]R_\text{H} \approx 1.09678 \times 10^{7}\; \rm m^{-1}[/tex].Let [tex]n_1[/tex] and [tex]n_2[/tex] denote the principal quantum number of the initial and final main energy level of that electron. (Both [tex]n_1\![/tex] and [tex]n_2\![/tex] should be positive integers; [tex]n_1 > n_2[/tex].)The Rydberg Equation gives the following relation:
[tex]\displaystyle \frac{1}{\lambda_\text{vac}} = R_\text{H} \cdot \left(\frac{1}{{n_2}^2}} -\frac{1}{{n_1}^2}\right)[/tex].
Rearrange to obtain and expression for [tex]\lambda_\text{vac}[/tex]:
[tex]\displaystyle \lambda_\text{vac} = \frac{1}{\displaystyle R_\text{H}\cdot \left(\frac{1}{{n_2}^2} - \frac{1}{{n_1}^2}\right)}[/tex].
In this question, [tex]n_1 = 7[/tex] while [tex]n_2 = 3[/tex]. Therefore:
[tex]\begin{aligned} \lambda_\text{vac} &= \frac{1}{\displaystyle R_\text{H}\cdot \left(\frac{1}{{n_2}^2} - \frac{1}{{n_1}^2}\right)} \\ &\approx \frac{1}{\displaystyle 1.09678 \times 10^{7}\; \rm m^{-1} \cdot \left(\frac{1}{3^2} - \frac{1}{7^2}\right)} \approx 1.0 \times 10^{-6}\; \rm m \end{aligned}[/tex].
Note, that [tex]1.0\times 10^{-6}\; \rm m[/tex] is equivalent to [tex]1000\; \rm nm[/tex]. That is: [tex]1.0\times 10^{-6}\; \rm m = 1000\; \rm nm[/tex].
Look up the speed of light in vacuum: [tex]c \approx 3.00\times 10^{8}\; \rm m \cdot s^{-1}[/tex]. Calculate the frequency of this photon:
[tex]\begin{aligned} f &= \frac{c}{\lambda_\text{vac}} \\ &\approx \frac{3.00\times 10^{8}\; \rm m\cdot s^{-1}}{1.0\times 10^{-6}\; \rm m} \approx 3.00 \times 10^{14}\; \rm Hz\end{aligned}[/tex].
Let [tex]h[/tex] represent Planck constant. The energy of a photon of wavelength [tex]f[/tex] would be [tex]E = h \cdot f[/tex].
Look up the Planck constant: [tex]h \approx 6.62607 \times 10^{-34}\; \rm J \cdot s[/tex]. With a frequency of [tex]3.00\times 10^{14}\; \rm Hz[/tex] ([tex]1\; \rm Hz = 1\; \rm s^{-1}[/tex],) the energy of each photon released in this transition would be:
[tex]\begin{aligned}E &= h \cdot f \\ &\approx 6.62607 \times 10^{-34}\; \rm J\cdot s^{-1} \times 3.00 \times 10^{14}\; \rm s^{-1} \\ &\approx 1.98 \times 10^{-19}\; \rm J\end{aligned}[/tex].
The energy of the transition between n = 7 and n = 3 is 1.96 × 10^-19 J while the frequency is 3 × 10^14 Hz.
Using the Rydberg Equation for energy;
ΔE = -RH(1/n^2final - 1/n^2initial)
Given that;
nfinal = 3
ninitial = 7
RH = 2.18 × 10^-18 J
ΔE = - 2.18 × 10^-18(1/3^2 - 1/7^2)
ΔE = - 2.18 × 10^-18(0.11 - 0.02)
ΔE = - 1.96 × 10^-19 J
For the second part;
Since the wavelength is 1000nm, we have;
λ = 1000nm
c = 3 × 10^8 m/s
f = ?
c = λf
f = c/λ
f = 3 × 10^8 m/s/1000 × 10^-9 m
f = 3 × 10^8 m/s/ 1 × 10^-6 m
f = 3 × 10^14 Hz
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A certain first-order reaction has a rate constant of 2.10×10−2 s−1 at 19 ∘C. What is the value of k at 58 ∘C if Ea = 82.0 kJ/mol ?
Answer:
K₂ = 1.12s⁻¹
Explanation:
Based on Arrhenius equation:
ln K₂/K₁ = -Ea/R (1/T₂ - 1/T₁)
Where K is rate constant,
R is gas constant (8.314J/molK),
T is absolute temperature (In K) Of 1, initial state and 2, final state.
ln K₂/K₁ = -Ea/R (1/T₂ - 1/T₁)
ln K₂/2.10x10⁻²s⁻¹ = -82000J/mol/8.314J/molK (1/(273.15 + 58) - 1/(273.15 + 19))
ln K₂ / 2.10x10⁻²s⁻¹ = 3.976
K₂ / 2.10x10⁻²s⁻¹ = 53.3
K₂ = 1.12s⁻¹
What are the properties of gas
Answer:
1) easy compressed
2) fills its container
3) far more space
Explanation:
A. In a separatory funnel containing ethyl acetate and 10% aqueous sodium bicarbonate (NaHCO3), which layer would contain the brominated aromatic compound?
Answer:
ethyl acetate layer
Explanation:
This question tests your knowledge of the principle of solvent extraction.
In solvent extraction, there is always an organic layer and an aqueous layer. The ethyl acetate is the organic layer while the sodium bicarbonate is the aqueous layer.
A brominated aromatic compound will be extracted into the organic layer (ethyl acetate layer).
Which are replenished MORE quickly than they are used?
A. energy resources
B. material resources
C. renewable resources
D. nonrenewable resources
Answer:c
Explanation: more expensive so people use nonrenewed energy more.
Identify the following reaction as an endothermic reaction, exothermic reaction, or both endothermic and exothermic:
Dissolving NH4Cl in water to make a cold pack.
Answer:
Endothermic reaction
Explanation:
Endothermic reactions are defined as the type of chemical reaction in which the system absorbs the energy from the surroundings and the temperature of the surrounding decreases while in Exothermic reactions, heat is released by the system to the surroundings and it makes the surrounding warm.
The given example is an "endothermic reaction" because the reaction between NH4Cl and water is making the surrounding cool (cold pack) due to the release of heat.
Hence, the correct answer is "endothermic reaction".
Why doesn't chromic acid oxidize tertiary alcohol?
Calculate the wavelength of light (in nm) of the spectral line of Hydrogen where an electron falls from the 6th Bohr orbit to the 3rd Bohr orbit.
a) 540 nm
b) 2000 nm
c) 1090 nm
d) 1050 nm
Answer:
The wavelength of light (in nm) of the spectral line of Hydrogen where an electron falls from the 6th Bohr orbit to the 3rd Bohr orbit is 1090nm
Explanation:
We know that , the wavelength of the light is calculated by Rydberg's formula-
[tex]\frac{1}{\pi} =R^2(\frac{1}{n^2_1} -\frac{1}{n^2_2})[/tex] [tex][n_2>n_1][/tex]
Here , R = Rydberg's constant [tex](1.097\times 10^7 m^-^1)[/tex]
Z = atomic number (for hydrogen , Z= 1)
[tex]n_2 =6 , n_1=3[/tex]
[tex]\pi =[/tex] wavelength of light
Now , putting the values in the Rydberg's formula ,
[tex]\frac{1}{\pi} =1.097\times10^7m^-^1(\frac{1}{3^2} -\frac{1}{6^2} )[/tex]
=[tex]1.097\times 10^7m^-^1 (\frac{4-1}{36} )[/tex]
=[tex]1.097\times 10^7m^-^1(\frac{3}{36} )[/tex]
=[tex]1.097\times 10^7m^-^1(\frac{1}{12} )[/tex]
[tex]\frac{1}{\pi}[/tex] = [tex]0.0914167\times 10^7m^-^1[/tex]
[tex]\pi=\frac{1}{0.0914167\times10^7m^-^1}[/tex]
[tex]\pi=10.9389\times10^-^7\\\pi=1093.89\times10^-^9m[/tex]
=1090nm
Hence , the wavelength of the light is 1090nm,, that is option D is correct.
All organelles that only plant cells have
Answer:
Cell wall, chloroplast, and vacuoles
Explanation:
Aspirin is a weak organic acid whose molecular formula is HC9H7O4. An aqueous solution of aspirin is prepared by dissolving 3.60 g/L. The pH of this solution is found to be 2.6. Calculate Ka for aspirin. (atomic mass: C
Answer:
Ka = 3.50x10⁻⁴
Explanation:
First, we need to convert the unit of 3.60 g/L to mol/L:
[tex] C_{C_{9}H_{8}O_{4}} = 3.60 \frac{g}{L}*\frac{1 mol}{180.16 g} = 0.0200 mol/L [/tex]
The reaction dissociation of aspirin in water is:
C₉H₈O₄ + H₂O ⇄ C₉H₇O₄⁻ + H₃O⁺
0.02 - x x x
The constant of the above reaction is:
[tex] Ka = \frac{[C_{9}H_{7}O_{4}^{-}][H_{3}O^{+}]}{[C_{9}H_{8}O_{4}]} [/tex]
[tex] Ka = \frac{x^{2}}{0.02 - x} [/tex]
To find Ka we need to find the value of x. We know that pH = 2.6 so:
[tex] pH = -log[H_{3}O^{+}] [/tex]
[tex] 2.6 = -log(x) [/tex]
[tex] x = 2.51 \cdot 10^{-3} M = [H_{3}O^{+}] = [C_{9}H_{7}O_{4}^{-}] [/tex]
Now, the concentration of C₉H₈O₄ is:
[tex] C_{C_{9}H_{8}O_{4}} = 0.02 - 2.51 \cdot 10^{-3} = 0.018 M [/tex]
Finally, Ka is:
[tex] Ka = \frac{[C_{9}H_{7}O_{4}^{-}][H_{3}O^{+}]}{[C_{9}H_{8}O_{4}]} = \frac{(2.51 \cdot 10^{-3})^{2}}{0.018} = 3.50 \cdot 10^{-4} [/tex]
Therefore, the Ka of aspirin is 3.50x10⁻⁴.
I hope it helps you!
When 60 mL of 0.22 M NH4Cl is added to 60 mL of 0.22 M NH3, relative to the pH of the 0.10 M NH3 solution the pH of the resulting solution will:____________.
Answer:
Will be more acidic
Explanation:
The equilibrium of NH3 in water is:
NH3(aq) + H2O(l) ⇄ NH4⁺(aq) + OH⁻(aq).
Where equilibrium constant, Kb, is:
Kb = 1.85x10⁻⁵ = [NH4⁺] [OH⁻] / [NH3]
From 0.10M NH3, the reaction will produce X of NH4⁺ and X of OH⁻ and Kb will be:
1.85x10⁻⁵ = [X] [X] / [0.10M]
1.8x10⁻⁶ = X²
X = 1.34x10⁻³ = [OH⁻]
As pOH = -log[OH⁻] = 2.87
And as pH = 14 - pOH
pH of the 0.10M NH3 is 11.13
Now, to find the pH of the NH4Cl and NH3 we need to use H-H equation for bases:
pOH = pKb + log [NH4⁺] / [NH3]
Where pKb is -log Kb = 4.74 and [] are moles of both compounds.
Moles of [NH4⁺] = [NH3] = 60mL, 0.060L*0.22M = 0.0132moles:
pOH = 4.74 + log [0.0132] / [0.0132]
pOH = 4.74
pH = 14 - 4.74 = 9.26
That means the pH of the resulting solution will be more acidic
Determine ΔH for the reaction CaCO3 → CaO + CO2 given these data: 2 Ca + 2 C + 3 O2 → 2 CaCO3 ΔH = −2,414 kJ C + O2 → CO2 ΔH = −393.5 kJ 2 Ca + O2 → 2 CaO ΔH = −1,270 kJ Write your answer using 4 significant figures, do not include units.
Answer:
The ΔH for the reaction is -456.5 KJ
Explanation:
Here we want to determine ΔH for the reaction;
Mathematically;
ΔH = ΔH(product) - ΔH(reactant)
In the case of the first reaction;
ΔH = ΔH(CaO) + ΔH(CO2) - ΔH(CaCO3) ...........................(*)
From the other reactions, we can get the respective ΔH for the individual molecule in the reaction
In second reaction;
Kindly note that for elements, molecule of gases, ΔH = 0
What this means is that throughout the solution;
ΔH(Ca) = 0 KJ
ΔH(O2) = 0 KJ
ΔH(C) = 0 KJ
Thus, in writing the equation for the subsequent chemical reactions, we shall need to write and equate the overall ΔH for the reaction to that of the product alone
So in the second reaction
ΔH = 2ΔH(CaCO3)
Thus;
-2414/2 = ΔH(CaCO3)
ΔH(CaCO3) = -1,207 KJ
Moving to the third reaction, we have;
ΔH = ΔH(CO2)
Hence ΔH(CO2) = -393.5 KJ
For the last reaction;
ΔH = ΔH(CaO)
Hence ΔH(CaO) = -1270 KJ
Going back to equation *
ΔH = ΔH(CaO) + ΔH(CO2) - ΔH(CaCO3)
Using the values of the ΔH of the respective molecules given above,
ΔH = -1270 + (-393.5) - (-1207)
ΔH = -456.5 KJ
A geochemist has determined by measurements that there are moles of tin in a sample of cassiterite. How many moles of oxygen are in the sample
The question is incomplete, the complete question is:
This is the chemical formula for cassiterite (tin ore): SnO2 A geochemist has determined by measurements that there are 13. moles of tin in a sample of cassiterite. How many moles of oxygen are in the sample? Round your answer to 2 significant digits.
Answer:
Explanation:
In SnO2, there are two moles of oxygen for each mole of tin.
Hence, if there are 13 moles of tin, then we should have 13 * 2 moles of oxygen. This gives us 26 moles of oxygen.
Hence there are 26 moles of oxygen.
The chemical formula for sumuric acid is H Son. In one molecule of sulfuric acid, there are____
A. two atoms of hellum
B. two atoms of oxygen
C. four atoms of oxygen
D. four atoms of sulfur oxide
Answer:
I want to say option C: four atoms of oxygen. Sorry if I'm wrong
A mixture of cyclopropane gas and oxygen is used as an anesthetic. Cyclopropane contains 85.7% C And 14.3% hydrogen by mass. At 50.0 degrees celcius and .984 atm pressure, 1.56 g cyclopropane has a volume of 1.00L.
Required:
What is the molecular formula of cyclopropane?
Answer:
C₃H₆
Explanation:
We'll begin by calculating the empirical formula for cyclopropane. This is illustrated below:
Carbon (C) = 85.7%
Hydrogen (H) = 14.3%
Divide by their molar mass
C = 85.7/12 = 7.14
H = 14.3/1 = 14.3
Divide by the smallest:
C = 7.14/7.14 = 1
H = 14.3/7.14 = 2
Therefore, the empirical formula for the cyclopropane is CH₂
Next, we shall determine the number of mole of cyclopropane.
This can be obtained as follow:
Temperature (T) = 50 °C = 50 °C + 273 = 323 K
Pressure (P) = 0.984 atm
Volume (V) = 1 L
Gas constant (R) = 0.0821 atm.L/Kmol
Number of mole (n) of cyclopropane =.?
PV = nRT
0.984 × 1 = n × 0.0821 × 323
Divide both side by 0.0821 × 323
n = 0.984 / (0.0821 × 323)
n = 0.0371 mole
Next, we shall determine the molar mass of cyclopropane. This can be obtained as follow:
Number of mole of cyclopropane = 0.0371 mole
Mass of cyclopropane = 1.56 g
Molar mass of cyclopropane =.?
Mole = mass /Molar mass
0.0371 = 1.56/Molar mass
Cross multiply
0.0371 × Molar mass = 1.56
Divide both side by 0.0371
Molar mass = 1.56 /0.0371
Molar mass of cyclopropane = 42.05 g/mol.
Finally, we shall determine the molecular formula for cyclopropane. This can be obtained as follow:
[CH₂]ₙ = 42.05
[12 + (2×1)]ₙ = 42.05
[12 + 2]ₙ = 42.05
14n = 42.05
Divide both side by 14
n = 42.05/ 14
n = 3
Thus,
[CH₂]ₙ => [CH₂]₃ => C₃H₆
Therefore, the molecular formula for cyclopropane is C₃H₆
The molecular formula of cyclopropane ([tex]CH_2[/tex]) is equal to [tex]C_3H_6[/tex]
Given the following data:
Percent mass of cyclopropane = 85.7%Percent mass of hydrogen = 14.3%Temperature = 50.0°C to Kelvin = [tex]273+50=323\;K[/tex]Pressure = 0.984 atm.Mass of cyclopropane = 1.56 grams.Volume of cyclopropane = 1.00 Liter.Scientific data:
Ideal gas constant, R = 0.0821L⋅atm/mol⋅KThe atomic weight of carbon (C) = 12 g/molThe atomic weight of hydrogen (H) = 1 g/molTo determine the molecular formula of cyclopropane:
First of all, we would determine the molar mass and number of moles of cyclopropane by using the ideal gas law equation;
[tex]PV=\frac{M}{MM} RT[/tex]
Where;
P is the pressure.V is the volume.M is the mass of gas.MM is the molar mass of gas.R is the ideal gas constant.T is the temperature.Making MM the subject of formula, we have:
[tex]MM = \frac{MRT}{PV} \\\\MM = \frac{1.56\;\times \;0.0821\times \;323}{0.984\;\times \;1}\\\\MM = \frac{41.3686}{0.984}[/tex]
Molar mass, MM = 42.04 g/mol.
For number of moles:
[tex]Number\;of\;moles = \frac{mass}{molar\;mass}\\\\Number\;of\;moles = \frac{1.56}{42.04}[/tex]
Number of moles = 0.0371 moles
Next, we would determine the empirical formula of cyclopropane:
For carbon (C):
[tex]C = \frac{85.7}{12}[/tex]
Carbon (C) = 7.1417
For hydrogen (H):
[tex]H = \frac{14.3}{1}[/tex]
Hydrogen (H) = 14.3
Simplest whole number ratio:
[tex]C = \frac{7.1417 }{7.1417 } =1[/tex]
[tex]H= \frac{14.3 }{7.1417 } =2[/tex]
Empirical formula of cyclopropane = [tex]CH_2[/tex]
Now, we can determine the molecular formula of cyclopropane:
[tex](CH_2)n = 42.04\\\\(12 + 1\times2)n=42.04\\\\14n=42.04\\\\n=\frac{42.04}{14}[/tex]
n = 3
Molecular formula of cyclopropane ([tex]CH_2[/tex]) = [tex](CH_2)_3 =C_3H_6[/tex]
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You need to make an aqueous solution of 0.243 M iron(III) chloride for an experiment in lab, using a 125 mL volumetric flask. How much solid iron(III) chloride should you add?
Answer:
5 g
Explanation:
From the question, we have,
Molarity of FeIII solution= 0.245 M
Volume of solution = 125 ml
From
number of moles= concentration × volume
We have;
Number of moles= 0.245 M × 125/1000
Number of moles = 0.031 moles
Molar mass of Fe III = 162.5g/moles
Mass of iron III = number of moles× molar mass = 0.031 × 162.5= 5 g
n
Which of the following is an example of a diatomic molecule?
2H
O2
CH4
H2O
Answer:
O2
Explanation:
Diatomic molecules are molecules that have 2 of either H,N,F,O,I,Cl, or Br. In this case, 2H is not correct because the 2 is in front of the element name. Diatomic molecules will have the two after which means that the molecule has these two elements together.
Aluminum metal and bromine liquid (red) react violently to make aluminum bromide (white powder). One way to represent this equilibrium is:
Al(s) + 3/2 Br2(l)AlBr3(s)
We could also write this reaction three other ways, listed below. The equilibrium constants for all of the reactions are related. Write the equilibrium constant for each new reaction in terms of K, the equilibrium constant for the reaction above.
1) 2 AlBr3(s) 2 Al(s) + 3 Br2(l)
2) 2 Al(s) + 3 Br2(l) 2 AlBr3(s)
3) AlBr3(s) Al(s) + 3/2 Br2(l)
Answer:
Explanation:
Al(s) + 3/2 Br₂(l) = AlBr₃(s)
K = [ AlBr₃] / [ Al] [ Br₂]³/²
K² = [ AlBr₃]² / [ Al ] ² [ Br₂]³
2 AlBr₃ = 2 Al(s) + 3 Br₂(l) =
K₁ = [ Al ] ² [ Br₂]³ / [ AlBr₃]²
K₁ = ( 1 / K² ) = K⁻²
2 ) 2 Al(s) + 3 Br₂(l) = 2 AlBr₃(s)
K₂ = [ AlBr₃ ]² / [ Al ]² [ Br₂ ]³
K₂ = K²
3 )
AlBr₃(s) = Al(s) + 3/2 Br₂(l)
K₃ = [ Al ] [ Br₂ ] ³/² / [ AlBr₃ ]
= ( 1 / K ) = K⁻¹
. What is the independent variable? (what scientist changes or makes different)Cory wants to see which cup will keep his coffee hottest. He usually drinks coffee out of a Styrofoam cup but decides to compare it to 3 different types of cups. Cory puts 250 ml of his favorite coffee at 95 degrees Celsius into a Styrofoam cup, a plastic cup, a glass cup, and a paper cup. He measures the temperature change of the coffee after 10 minutes.
Answer: the type of cup
Explanation: the independent variable is what you change in your experiment, to find out the different results, in this experiment the factor that they are changing in order to see which outcome is best, is the type of cup.
What is the best way to organize desert several several million different types of organisms on earth
Answer:
The desert should be divided into different types based on its properties. The organisms living in specific type of desert should be named accordingly.
Explanation:
There are usually five major types of desert in the world. Tropical, rainy, semi arid desert, coastal desert and dry desert. There are many different types of organisms living in these deserts. The biodiversity has made it difficult for the humans to analyse and identify the millions of different types. The best way is to organize and name the organisms that live in specific types of deserts.
1. What step dogs every scientific experiment begin with?
A hypothesis
B. procedures
C conclusion
D. question/problem
Nicotinic acid, HC6H4NO2, is a B vitamin. It is also a weak acid with Ka = 1.4 × 10-5. Calculate [H+] and the pH of a 0.041 M solution of HC6H4NO2.
Answer:
[H+] = 7.576x10⁻⁴M
pH = 3.12
Explanation:
Based on the equilibrium of the nicotinic acid in water:
HC6H4NO2(aq) + H2O(l) ⇄ C6H4NO2-(aq) + H3O+(aq)
Ka = [C6H4NO2-] [H3O+] / [HC6H4NO2]
As both C6H4NO2-(aq) and H3O+(aq) comes from the same equilibrium, we can approximate their concentration as X and replace:
Ka = [C6H4NO2-] [H3O+] / [HC6H4NO2]
1.4x10⁻⁵ = [X] [X] / [0.041M]
5.47x10⁻⁷ = X²
7.576x10⁻⁴M = X = [H+]And as pH is defined as -log [H⁺]
pH = 3.12s the purpose of the CaCl2 drying tube? What chemical reaction is it preventing (please supply a mechanism).
Answer:
See explanation
Explanation:
A drying tube prevents moisture from contaminating the reactants. The drying tube contains CaCl2 a hygroscopic material whose function is to absorb the moisture so that it does not react with the Grignard reagent. Without the desiccating action of CaCl2, moisture will enter the reaction chamber,contaminating the reactants.
If water reacts with the Grignard reagent, an alkane is formed. The mechanism of this reaction is shown in the image attached. R here represents the alkyl moiety of the Grignard reagent.
A sample is found to contain 57.2 % N a H C O 3 NaHCOX3 by mass. What is the mass of NaHCO 3 in 4.25 g of the sample
Answer:
The mass of N a H C O 3 present is 2.431 g
Explanation:
The sample contains 57.2 % N a H C O 3 by mass.
To find the mass of N a H C O 3 in the sample, we need to find what the equivalent of 57.2 %.
Mass of N a H C O 3 = Percentage Composition * Mass of sample
Mass of N a H C O 3 = 57.2 / 100 * 4.25
Mass of N a H C O 3 = 2.431 g
The mass of N a H C O 3 present is 2.431 g
The mass of the compound (NaHCO₃) contained in 4.25 g is 2.431 g.
The given parameters;
percentage composition of the compound, = 57.2%mass of the compound (NaHCO₃) = 4.25The mass of the compound (NaHCO₃) contained in 4.25 g is calculated by the finding its equivalent in the given percent composition as follows;
[tex]mass \ = \frac{57.2}{100} \times 4.25\\\\mass = 2.431 \ g[/tex]
Thus, the mass of the compound (NaHCO₃) contained in 4.25 g is 2.431 g.
Learn more about percentage composition here: https://brainly.com/question/20065048
the mass number of Fe is 56 . how many neutron are there in a single Fe atom
Answer:
30 neutrons
Explanation:
Since the mass of the iron nuclide is 56 , there must be 56−26=30 neutrons, 30 massive, neutral particles in this iron nucleus.
For which of the following processes would S° be expected to be most positive? a) O2(g) + 2H2(g) 2H2O(g) b) H2O(l) H2O(s) c) NH3(g) + HCl(g) NH4Cl(g) d) 2NH4NO3(s) 2N2(g) + O2(g) + 4H2O(g) e) N2O4(g) 2NO2(g) 12. Which of the following statements is
Answer:
Explanation:
a) O₂(g) + 2H₂(g) = 2H₂O
b) H₂O(l) = H₂O(s)
c) NH₃(g) + HCl(g) = NH₄Cl(g)
d) 2NH₄NO₃(s) = 2N₂(g) + O₂(g) + 4H₂O(g)
e) N₂O₄(g) = 2NO₂(g)
ΔS is positive when there is increase in disorderliness. It happens when there is increase in volume .
Increase is volume is maximus in the following reaction.
d) 2NH₄NO₃(s) = 2N₂(g) + O₂(g) + 4H₂O(g)
in this reaction solid NH₄NO₃ is changed to 7 x 22.4 L of gases so there is maximum increase in volume . Hence maximum increase in entropy . Hence ΔS is most positive .
