Apowder contains benzoic acid mixed with starch. a student finds that a 2.505 g sample of this powder requires 35.3 ml of a 0.107m sodium hydroxide solution for the acid to be neutralized. what is the percent by mass of benzoic acid in the powder?

Answer is:  the percent by mass of benzoic acid in the powder is 18.41%.

1) Balanced chemical reaction:

C₆H₅COOH(aq) + NaOH(aq) → C₆H₅COONa(aq) + H₂O(l).

V(NaOH) = 35.3 mL ÷ 1000 mL/L.

V(NaOH) = 0.0353 L; volume of the sodium hydroxide.

c(NaOH) = 0.107 mol/L; molarity of the sodium hydroxide.

n(NaOH) = c(NaOH) · V(NaOH).

n(NaOH) = 0.0353 L · 0.107 mol/L.

n(NaOH) = 0.00378 mol; amount of the sodium hydroxide.

2) From balanced chemical reaction: n(NaOH) : n(C₆H₅COOH).

n(NaOH) = n(C₆H₅COOH).

n(C₆H₅COOH) = 0.0038 mol; amount of the benzoic acid.

M(C₆H₅COOH) = 122.12 g/mol; molar mass of the benzoic acid.

m(C₆H₅COOH) = n(C₆H₅COOH) · M(C₆H₅COOH).

m(C₆H₅COOH) = 0.0038 mol · 122.12 g/mol.

m(C₆H₅COOH) = 0.461 g; mass of the benzoic acid.

m(powder) = 2.505 g; mass of a powder.

ω(C₆H₅COOH) = m(C₆H₅COOH) ÷ m(powder) · 100%.

ω(C₆H₅COOH) = 0.461 g ÷ 2.505 g · 100%.

ω(C₆H₅COOH) = 18.41%; mass percentage of the benzoic acid in a powder.

chemistry sucks a**

explanation:

the ozone layer acts as a filter for the shorter wavelength and highly hazardous ultraviolet radiation (uvr) from the sun, protecting life on earth from its potentially harmful effects. when the sky is clear, there is an inverse relationship between stratospheric ozone and solar uvr measured at the earth's surface.