[dzidza]

2 HCL +Zn  ZnCL2 +H₂

when you use 25ml of 4.0 M HCL to produce H₂ gas. how many grams of zinc does it react with? what volume of H₂ gas is produced at STP?

[dzidza]

3Fe + 2Au(NO₃)₃  3Fe(NO₃)₂ + 2Au

throwing some scrap iron in a gold nitrate solution causes the gold metal to precipitate. How much  0.50M gold nitrate solution would react with 224 grams of iron metal?

b) sea water is about 0.50 M NaCl. to produce CL₂ gas a company evaporates sea water, melts the NaCl and runs electricity through it. 2Nacl Δ :rarrow:2Na + Cl₂ how many litres of sea water are needed to fill a tank with 1 120 000 litres of chlorine gas at STP?

[Arkcon]

dzidza:, I hope you don't mind that I merged our two questions.  They seem to work the the same concepts, so the answer to one, will likely help you with the other.  Also, please trouble yourself to re-read our Forum Rules{click}.  You agreed to them when you signed up, and we expect you to follow them.  This is a learning forum, we want to help you help yourself. 

Your problems mention a gas at STP, do you know what that stands for, and can you use it in a formula, found in your class notes or textbook, that relates STP to volume and amount of gas?

[KungKemi]

Right, so I'm not going to exactly provide the answer dzidza, but I'll try and use another question as an example of how to solve your types of questions.

3H₂ + N₂  2NH₃. Also written as: 3 mol hydrogen gas + 1 mol nitrogen gas  2 mol ammonia gas

Right, so an example question would be to determine how many litres of hydrogen gas at STP is required to produce 15 g of ammonia gas. Okay, so with every stoichiometry question the general premise is converting mol of 1 substance to mol of another substance (whether it be a product or reactant).

This mol-ratio is dependent upon the provided chemical equation. For example, the mol ratio required for this question is 3 mol H₂ = 2 mol NH₃, or 3 mol H₂ is required to produce 2 mol of NH₃.

Rightio, so, working from here, one simply converts mass of ammonia gas to mol ammonia gas (using molar mass), to mol hydrogen gas (using mol ratio), and finally to volume of hydrogen gas at STP (1 mol = 22.4L).

The calculations look something like this:

15 g NH₃ × (1mol NH₃/17.0 g NH₃) × (3mol H₂/2mol NH₃) × (22.4L H₂/1mol H₂) = 30L of H₂

Always answer with a worded answer:

"As such, 30 litres of hydrogen gas is required to produce 15.0 g of ammonia gas."

In this case, I use dimensional analysis (it's just easier for me), but the way of answering these kinds of questions require similar variations to the working-out above.

The way to work out your provided questions are similar to the method used above, however, it just requires a few more steps (like doing something with that molarity).

I hope this helps
KungKemi

[AWK]

Right, so an example question would be to determine how many litres of hydrogen gas at STP is required to produce 15 g of ammonia gas

for 15 g of NH3 - 30 L is OK
_{"As such, 30 litres of hydrogen gas is required to produce 15.0 g of ammonia gas."}
but for 15.0 g should be 29.6 L.

[KungKemi]

Right, so an example question would be to determine how many litres of hydrogen gas at STP is required to produce 15 g of ammonia gas

for 15 g of NH3 - 30 L is OK
_{"As such, 30 litres of hydrogen gas is required to produce 15.0 g of ammonia gas."}
but for 15.0 g should be 29.6 L.

That is true, if I use three significant figure, likewise, I should use it for my answer.

Thanks for the pickup, AWK.