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NeX [460]
3 years ago
13

Acetic acid (HC2H3O2, Ka=1.8x10^-5) is a weak acid. Calculate the pH of an aqueous solution of .25M acetic acid.

Chemistry
1 answer:
tensa zangetsu [6.8K]3 years ago
5 0

Answer: The pH of an aqueous solution of .25M acetic acid is 2.7

Explanation:

HC_2H_3O_2\rightarrow H^+C_2H_3O_2^-

 cM              0             0

c-c\alpha        c\alpha          c\alpha  

So dissociation constant will be:

K_a=\frac{(c\alpha)^{2}}{c-c\alpha}

Give c= 0.25 M and \alpha = ?

K_a=1.8\times 10^{-5}

Putting in the values we get:

1.8\times 10^{-5}=\frac{(0.25\times \alpha)^2}{(0.25-0.25\times \alpha)}

(\alpha)=0.0084

[H^+]=c\times \alpha

[H^+]=0.25\times 0.0084=0.0021

Also pH=-log[H^+]

pH=-log[0.0021]=2.7

Thus pH is 2.7

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Answer:

Explanation:

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4 0
2 years ago
An element and an atom are different but related because
White raven [17]

Answer:

c) An element is made up of all the same type of atom

Explanation:

Atoms are the smallest unit of an element that consists of protons, electrons and neutrons in its structure. An element is the smallest part of a chemical substance that cannot be disintegrated i.e. it cannot be broken down further.

Atoms and elements are different in many ways but they are connected in the sense that an element contains only one type of atoms. For example, aluminum element is made up of only aluminum atoms. Different atoms form a molecule but same atoms form an element.

4 0
3 years ago
A student used 1.168g of an unknown weak acid and titrated it against 28.75 mL of 0.105M NaOH to reach the equivalence point. Wh
Vaselesa [24]

Answer:

The molar mass of the unknown acid is 386.8 g/mol

Explanation:

Step 1: Data given

Mass of the weak acid = 1.168 grams

volume of NaOH = 28.75 mL = 0.02875 L

Molarity of NaOH = 0.105 M

Since we only know 1 equivalence point, we suppose the acid is monoprotic

Step 2: Calculate moles NaOH

Moles NaOH = molarity NaOH * volume NaOH

Moles NaOH = 0.105 M * 0.02875 L

Moles NaOH = 0.00302 moles

We need 0.00302 moles of weak acid to neutralize the NaOH

Step 3: Calculate molar mass of weak acid

Molar mass = mass / moles

Molar mass = 1.168 grams / 0.00302 moles

Molar mass = 386.8 g/mol

The molar mass of the unknown acid is 386.8 g/mol

3 0
3 years ago
A hot air balloon is filled with 15 moles helium gas and 5 moles nitrogen gas. What is the volume of the balloon at 1.01 atm and
kvasek [131]

<u>Given:</u>

Moles of He = 15

Moles of N2 = 5

Pressure (P) = 1.01 atm

Temperature (T) = 300 K

<u>To determine:</u>

The volume (V) of the balloon

<u>Explanation:</u>

From the ideal gas law:

PV = nRT

where P = pressure of the gas

V = volume

n = number of moles of the gas

T = temperature

R = gas constant = 0.0821 L-atm/mol-K

In this case we have:-

n(total) = 15 + 5 = 20 moles

P = 1.01 atm and T = 300K

V = nRT/P = 20 moles * 0.0821 L-atm/mol-K * 300 K/1.01 atm = 487.7 L

Ans: Volume of the balloon is around 488 L


3 0
3 years ago
1. Which of the following is a correctly written thermochemical equation?
WITCHER [35]

Explanation:

1. Thermochemical equation is balance stoichiometric chemical equation written with the phases of the reactants and products in the brackets along with the enthalpy change of the reaction.

The given correct thermochemical reactions are:

Fe(s)+O_2(g)\rightarrow Fe_2O_3(s),\Delta H = 3,926 kJ&#10;

C_3H_8(g)+5O_2 (g)\rightarrow 3CO_2 (g)+4H_2O(l),\Delta H= 2,220 kJ/mol

2. Phase change affect the value of the enthalpy change of the thermochemical equation. This is because change in phase is accompanied by change in energy. For example:

H_2O(s)\rightarrow H_2O(g),\Delta H_{s}=51.1 kJ/mol

H_2O(l)\rightarrow H_2O(g),\Delta H_{v}=40.65 kJ/mol

In both reaction phase of water is changing with change in energy of enthalpy of reaction.

7 0
3 years ago
Read 2 more answers
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