- #1

- 158

- 0

## Homework Statement

The reaction between zinc and hydrochloric acid is carried out as a source of hydrogen gas in the laboratory:

[itex]Zn(s)+2 HCl(aq)\rightarrow ZnCl_2(aq)+H_2(g)[/itex]

If 325 mL of hydrogen gas is collected over water at 25°C at a total pressure of 748 mm Hg, how many grams of Zn reacted?

## Homework Equations

[itex]PV=nRT[/itex]

[itex]M=\frac{m}{n}[/itex]

## The Attempt at a Solution

Pressure in atmosphere:

[itex]\frac{748 mm Hg}{760 mm Hg/atm}=0.984 atm[/itex]

Moles of Zn:

[itex]n=\frac{PV}{RT}=\frac{0.984 atm\cdot 0.325 L}{0.0821\frac{L\cdot atm}{mol\cdot K}\cdot (25+273)K}=0.013 mol[/itex]

Grams of Zn:

[itex]m=M\cdot n=65.39g/mol\cdot 0.013 mol=0.85 g[/itex]

I'm supposed to get 0.828 grams so I don't know what it is that I'm doing wrong?