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3 years ago

I need help with my lab report

Chemistry

1 answer:

stich3 [128]3 years ago

7 0

Answer:

learn more. feather learning can help

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Calculate the pKa of lactic acid (CH3CH(OH)COOH) given the following information. 3.005 grams of potassium lactate are added to

snow_lady [41]

Answer:

$\displaystyle \text{p} K_a \approx 3.856$

Explanation:

Because 3.005 grams of potassium lactate is added to 100. mL of solution, its concentration is:

$\displaystyle \begin{aligned} \left[ \text{KC$_3$H_$_5$O$_3$}\right] & = \frac{3.005\text{ g KC$_3$H_$_5$O$_3$}}{100.\text{ mL}} \cdot \frac{1\text{ mol KC$_3$H_$_5$O$_3$}}{128.17 \text{ g KC$_3$H_$_5$O$_3$}} \cdot \frac{1000\text{ mL}}{1\text{ L}} \\ \\ &= 0.234\text{ M}\end{aligned}$

By solubility rules, potassium is completely soluble, so the compound will dissociate completely into potassium and lactate ions. Therefore, [KC₃H₅O₃] = [C₃H₅O₃⁺]. Note that lactate is the conjugate base of lactic acid.

Recall the Henderson-Hasselbalch equation:

$\displaystyle \begin{aligned}\text{pH} = \text{p}K_a + \log \frac{\left[\text{Base}\right]}{\left[\text{Acid}\right]} \end{aligned}$

[Base] = 0.234 M and [Acid] = 0.500 M. We are given that the resulting pH is 3.526. Substitute and solve for p<em>Kₐ</em>:

$\displaystyle \begin{aligned} (3.526) & = \text{p}K_a + \log \frac{(0.234)}{(0.500)} \\ \\ 3.526 & = \text{p}K_a + (-0.330) \\ \\ \text{p}K_a & = 3.856\end{aligned}$

In conclusion, the p<em>Kₐ </em>value of lactic acid is about 3.856.

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2 years ago

Does anyone know how to do number 15?

vovikov84 [41]

Answer:

yes i do 980

Explanation:

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3 years ago

Please please help me please please

uranmaximum [27]

Answer: 1. A, 2.B, 3. D, 4. B, 5. C

Explanation:

i have P.E. too lol have a great day!

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3 years ago

What is the happens in electrolysis if the electrolyte solidifies?

lidiya [134]

Answer: For example, if electricity is passed through molten lead bromide, the lead bromide is broken down to form lead and bromine. This is what happens during electrolysis: Positively charged ions move to the negative electrode during electrolysis. ... Negatively charged ions move to the positive electrode during electrolysis.

Explanation:

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3 years ago

Hydrochloric acid + aluminum hydroxide ®

makkiz [27]

The answer is C. and D. water and aluminum

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