Chemistry, 13.07.2019 20:00 trentonthreats5073

What mass of sodium benzoate should be added to 160.0 ml of a 0.17 m benzoic acid solution in order to obtain a buffer with a ph of 4.30?

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Answer from: Tsumiki

Answer :

The mass of sodium benzoate that can be added to benzoic acid is 5.07 g

Explanation :

The problem can be solved with the help of Henderson-Hasselbalch equation.

Step 1 : Find concentration of sodium benzoate

The equation is given below.

$p^{H} = p^{Ka} + log \frac{[Base]}{[Acid]}$

We have been given,

pH = 4.30

[Acid] = 0.17 M

Ka of benzoic acid can be found out using standard reference table which is 6.5 x 10⁻⁵

pKa = - log (Ka)

pKa = - log (6.5 x 10⁻⁵)

pKa = 4.19

Let us plug in the above values in Henderson equation.

$4.30 = 4.19 + log \frac{[Base]}{(0.17M)}$

$0.11 = log \frac{[Base]}{0.17}$

$10^{0.11} = 10^{log \frac{[Base]}{0.17}}$

The functions $10^{log}$ cancel out each other.

$10^{0.11} = \frac{[Base]}{0.17}$

$1.29 = \frac{[Base]}{0.17}$

[Base] = 0.22 M

The base in this case is sodium benzoate.

Therefore concentration of sodium benzoate is 0.22 M.

Step 2 : Find moles of sodium benzoate

The volume of the solution is 160 mL.

Volume in L = $160 mL\times \frac{1L}{1000mL}= 0.16 L$

Moles of sodium benzoate can be found as,

$mole=concentration \times volume(L)$

$mole=0.22 mol/L \times 0.16 L$

mole=0.0352 mol

Moles of sodium benzoate are 0.0352

Step 3 : Find mass of sodium benzoate

Mass of sodium benzoate can be calculated as

Mass in grams = Moles x Molar mass

The formula of sodium benzoate is C₇H₅O₂Na.

Molar mass of sodium benzoate = 7 x 12.01 + 5 x 1.01 + 2 x 16 + 22.98

Molar mass of sodium benzoate = 144.1

Mass of sodium benzoate = $0.0352 mol \times 144.1 \frac{g}{mol}$

Mass of sodium benzoate = 5.07 g

5.07 grams of sodium benzoate should be added to the given volume of benzoic acid.

Answer from: Quest

a rain shadow is a dry region of land on the side that is protected against the prevailing winds of a mountain range. the prevailing winds are the winds that occur most of the time in a particular place of the earth

prevailing winds carry air toward the mountain range. as the air rises up over a mountain range, the air cools, water vapor condenses, and clouds form. on this side of the mountains, called the windward side, precipitation falls in the form of rain or snow. this dry air produces a rain shadow.

Answer from: Quest

each column of the table is called a group. elements in a group share similar properties. groups are read from top to bottom. metal. metalloid. nonmetal. solid. liquid. gas. fe. hg. o. 2. 3. 4. 5. 6. 7. 8. 9. 2. beryllium. 9.012. 4. sodium. 22.990. 11. 3. magnesium. 24.305. 12. potassium. 39.098. 19. 4. calcium. 40.078. 20. i guess i

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What mass of sodium benzoate should be added to 160.0 ml of a 0.17 m benzoic acid solution in order...