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oksano4ka [1.4K]
2 years ago
9

PLEASE HELP ME ANSWER THESE QUESTIONS!

Chemistry
1 answer:
madam [21]2 years ago
8 0

Answer:

1. 0.35 moles NaOH

2. 5.10x10^{-4} moles H_2SO_4

3. 505.4 g Pb

4. 1.46 g HCl (if that is wrong it's 1.5 g HCl due to sig figs)

5. 3.01x10^{23} atoms of Ag

6. 2x10^{-10} atoms of Cu

Explanation:

1. The mass of NaOH is 40g. 22.99(Na)+16(O)+1.01(H)=40 g

14 g NaOH *\frac{1 mol NaOH}{40 g NaOH} = 0.35 moles of NaOH

2. Mass of H_{2} SO_{4} = 2(1.01)+32.06+4(16) = 98.08

0.05 g H_2SO_4 ×\frac{1 mol H_2SO_4}{98.08g H_2SO_4} = 5.10 x10^{-4}

3. mass of Pb = 106.4 g

4.75 moles Pb×\frac{106.4 g Pb}{1 mol Pb} =505.4 g Pb

4. mass of HCl = 1.01 +35.45 = 36.36 g

0.04 mol HCl x \frac{36.46 g HCl}{1 mol HCl} = 1.456 = 1.5

5. 5.00 mol Ag x\frac{6.022x10^{23} atoms }{1mol Ag} = 3.01x10^{24} atoms

6. 3x10^{-10} moles Cu x\frac{6.022x10^{23} atoms}{1 mol Cu} = 1.8668x10^{14}= 2x10^{14} atoms of Cu

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<u>Answer:</u> The pH change of the buffer is 0.30

<u>Explanation:</u>

To calculate the pH of basic buffer, we use the equation given by Henderson Hasselbalch:

pOH=pK_b+\log(\frac{[\text{conjugate acid}]}{[\text{base}]})

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We are given:

pK_b = negative logarithm of base dissociation constant of aniline  = 9.13

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Putting values in equation 1, we get:

pOH=9.13+\log(\frac{0.306}{0.418})\\\\pOH=8.99

To calculate pH of the solution, we use the equation:

pH+pOH=14\\pH_{initial}=14-8.99=5.01

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Volume of solution = 1 L

Putting values in above equation, we get:

\text{Molarity of HCl}=\frac{0.124}{1L}\\\\\text{Molarity of HCl}=0.124M

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                   C_6H_5NH_2+HCl\rightarrow C_6H_5NH_3^++Cl^-

<u>Initial:</u>           0.418        0.124           0.306

<u>Final:</u>             0.294          -                0.430

Calculating the pOH by using using equation 1:

pK_b = negative logarithm of base dissociation constant of aniline  = 9.13

[C_6H_5NH_3^+]=0.430M

[C_6H_5NH_2]=0.294M

pOH = ?

Putting values in equation 1, we get:

pOH=9.13+\log(\frac{0.430}{0.294})\\\\pOH=9.29

To calculate pH of the solution, we use the equation:

pH+pOH=14\\pH_{final}=14-9.29=4.71

Calculating the pH change of the solution:

\Delta pH=pH_{initial}-pH_{final}\\\\\Delta pH=5.01-4.71=0.30

Hence, the pH change of the buffer is 0.30

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