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damaskus [11]
3 years ago
8

A buffer solution is prepared from equal volumes of 0.200 M acetic acid and 0.600 M sodium acetate. Use 1.80 x 10−5 as Ka for ac

etic acid. (a) What is the pH of the solution? (b) Is the solution acidic or basic? (c) What is the pH of a solution that results when 3.00 mL of 0.034 M HCl is added to 0.200 L of the original buffer
Chemistry
1 answer:
Anika [276]3 years ago
8 0

Answer:

a. pH = 5.22

b. Acidic.

c. pH = 5.14

Explanation:

a. It is possible to find the pH of a buffer using Henderson-Hasselbalch equation (H-H equation):

pH = pKa + log₁₀ [A⁻] / [HA]

<em>Where pKa is -log Ka (For acetic acid =  4.74), [A⁻] is molar concentration of conjugate base (Acetate salt) and [HA] concentration of the weak acid (Acetic acid).</em>

Replacing:

pH = 4.74 + log₁₀ [0.600M] / [0.200M]

<em>You use the concentration of the acetic acid and sodium acetate because you're adding equal volumes, doing the ratio of the species the same</em>

<em />

<h3>pH = 5.22</h3><h3 />

b. As the solution has a pH lower that 7.0, it is considered as a <em>acidic solution.</em>

<em></em>

c. When you add HCl to the buffer, the reaction is:

CH₃COO⁻ + HCl → CH₃COOH + Cl⁻

<em>Where acetate ion reacts with the acid producing acetic acid.</em>

As you have 0.200L of the buffer, 0.100L are of the acetate ion and 0.100L of the acetic acid. Initial moles of both compounds and moles of HCl added are:

CH₃COO⁻: 0.100L ₓ (0.600mol / L) = 0.0600 moles

CH₃COOH: 0.100L ₓ (0.200mol / L) = 0.0200 moles

HCl: 3.0mL = 3x10⁻³L ₓ (0.034mol / L) =  0.00010 moles HCl

The moles added of HCl are the same moles you're consuming of acetate ion and producing of acetic acid. Thus, moles after the reaction are:

CH₃COO⁻: 0.0600 moles - 0.0001 moles = 0.0509 moles

CH₃COOH: 0.0200 moles + 0.0001 moles = 0.0201 moles

Replacing in H-H equation:

pH = 4.74 + log₁₀ [0.0509moles] / [0.0201moles]

<h3>pH = 5.14</h3>

<em />

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8 0
3 years ago
For the chemical reaction, 2HCl + Ca(OH)2 ➡️ CaCl2 + 2H2O what mass of calcium hydroxide in grams is needed to produce 3.63 mol
wlad13 [49]

Answer:

2HCl (aq) + Ca

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let us calculate the number of moles , as per the chemical reactions;

2 moles of HCl solution reacts with one mole Calcium Hydroxide

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One mole of HCl has mass : 36.5 g/mol, two moles of HCl will have mass, 73 g.

One mole of Ca

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as per equation; 73 g of HCl reacts with 74.1 g of Ca

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1g of HCl reacts with 74.1g / 73 of Ca

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2

1g of HCl reacts with 1.015 g of Ca

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2

NOW AS PER THE QUESTION MOLARITY AND VOLUME OF HYDROCHLORIC ACID IS GIVEN, IT CAN BE USED TO CALCULATE THE MASS OF HYDROCHLORIC ACID IN THE SOLUTION.

NUMBER OF MOLES of HCl ; Molarity of solution x Volume of Solution

# of moles of HCl = (0.40 mol/L ) x 350 mL

= (0.40 mol/L ) x 0.350 L = 0.14 mol

mass of HCl that makes 0.14 mol of HCl = # of moles x molar mass of HCl

mass of HCl = 0.14 mol x 36.5 g/ mol

mass of HCl = 5.11g

As per Stoichiometry , 1g of HCl reacts with 1.015 g of Ca

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O

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, 5.11g of HCl can react with 5.11 x 1.015 = 5.1865 g or 5.2 g of

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The correct option is;

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The penalties that could be faced includes

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7 0
3 years ago
Carbon dioxide, when it is at -145 degreesC has a density of 2.54 g/L. What is the pressure in torr??
Black_prince [1.1K]

Answer: The pressure in torr is 461 torr

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PV=nRT

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T = temperature =-145^0C=(273-145)K=128K

Number of moles (n) can be written as:

n=\frac{m}{M}

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The relation becomes:

PM=dRT  

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5 0
3 years ago
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Leni [432]

Answer : The energy required to heat of 1.50 kg iron is, 1.5\times 10^4J

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c = specific heat of iron = 0.450J/g^oC

T_1 = initial temperature  = -7.8^oC

T_2 = final temperature  = 15.0^oC

Now put all the given value in the above formula, we get:

Q=1500g\times 0.450J/g^oC\times (15.0-(-7.8))^oC

Q=15390J=1.5\times 10^4J

Therefore, the energy required to heat of 1.50 kg iron is, 1.5\times 10^4J

6 0
3 years ago
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