Question

If 62.8 g Ca react with 92.3 g HCl according to the reaction below, how many grams of hydrogen gas will be produced, and how many grams of the excess reactant will be left over?

Unbalanced equation: Ca + HCl → CaCl2 + H2

Be sure to show all of your work.

@Nurali

Answer 1

balance the reaction first

Answer 2

I don't know how, I am so lost in my chemistry class it's scary

Answer 3

Balance the equation

Ca + 2HCl -------> CaCl2 + H2


moles = mass / molar mass

moles Ca = 62.8 g / 40.08 g/mol = 1.5669 mol
moles HCl = 92.3 g / 36.458 g/mol = 2.532 mol

The balanced equation tells you that
1 mole Ca needs 2 moles HCl to fully react
So moles HCl needed to react all the Ca = 2 x moles Ca
= 2 x 1.5669 mol
= 3.1338 mol HCl needed

But you are only give 2.532 mol HCl, which means you don't have enough to react all the Ca, so HCl is limiting and Ca is in excess.

The maximum amount of H2 possible is if all the limiting reagent reacts.
2 moles HCl reacts to give 1 mole H2
So moles H2 possible = 1/2 x moles HCl
= 1.2 x 2.532 mol
= 1.266 moles H2

mass H2 = molar mass x moles
= 2.016 g/mol x 1.266 mol
= 2.55 g H2


work out how many moles of Ca you will need
1 mole Ca reacts with 2 moles HCl
So moles Ca = 1/2 x moles HCl
= 1.266 mol Ca used

moles Ca left over = amount provided - amount used
= 1.5669 mol - 1.266 mol
= 0.3009 mol

mass = molar mass x moles
= 40.08 g/mol x 0.3009 mol
= 12.1 g

Answer 4

Ca + HCl → CaCl2 + H2
count number of Ca, H, and Cl on the right and left side of the arrow
left side:
Ca - 1
H - 1
Cl - 1
right side
Ca -1
H -2
Cl -2
as you can see there are two of H and Cl on the right side so
we can write 2HCl on the left side to equal their numbers on both sides
Ca + 2HCl → CaCl2 + H2

Answer 5

wow that was
fast? o.o @Nurali

Answer 6

Wow. How do y'all know this stuff? Somy, can you give a medal to Nurali so I can give you one?

Answer 7

Thanks @Somy

Answer 8

i already did lol
that's too good

Answer 9

Thank you guys!!!

Answer 10

no problem tho credits go mostly to @Nurali :3

Answer 11

My Pleasure @Redneck1444