Asked by Shine bright shine far

Zn + 2HCl ---> ZnCl2 + H2(g)
What mass of zinc is needed to produce 115 mL of hydrogen?

t's given 115 mL of hydrogen, so can convert to 115/1000/22,4 = 0.0051 moles H2
- the ratio between HCl and H2 is 2 : 1, so the moles of HCl needed for this reaction is 0.01
- the ratio between Zn and H2 is 1 : 1, so the moles of Zn needed for this reaction is 0.0051
so the mass of Zn need is 0.0051*65 = 0.3315 (g)

How many moles of HCl are needed for the reaction? (5 marks)
Answered by Shine bright shine far
confused by moles part
Answered by Shine bright shine far
moles HCl needed = 2 x 0.0051 since stoichiometric ratio is 2:1
moles HCl = 0.01 moles
Answered by oobleck
You are correct in saying that
the ratio between HCl and H2 is 2 : 1, so the moles of HCl needed for this reaction is 0.01
Answered by Damon
yes if at Standard temp and pressure, 22.4 liters/mol
so
0.115 liters / 22.4 = 0.00513 mols of H2 and of Zn
so yes 0.00513 mols * 65.4 grams/mol = 0.336 grams of zinc
close enough we agree

Now for every mol of H2 you need 2 mols of HCl so we agree again
2 * 0.00513 = 0.01 mols HCl
Answered by astro
this curriculum has been used for a few years and all the answers are online XD
Answered by waddle
yup lol i've seen some of the exact same questions online from posts that are 9 yrs ago, think it goes further back if I recall based on some others haha.
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