Stoichiometry - Chemistry HELP!?

Question

1) What mass of sodium metal must react with water to produce 0.540 mol of hydrogen gas? (Recall the rule for the formula for water in single and double replacemtn reactions to help you with this equation.)

2) What mass of calcium carbonate will be produced by the reaction of 0.962 mol of calcium hydroxide with carbon dioxide to produce calcium carbonate and water?

3) In the first step in the production of sulfuric acid, sulfur is burned in the air to produce sulfur dioxide. How many moles of oxygen are required to react with 160 g of sulfur.

4) How many moles of hydrofluoric acid may be produced by the addition of sufficient sulfuric acid to 7.81 g o solid calcium fluoride?

*Could I have the steps and explanation please. I really don't understand.

Thank you so much.

Answer 1

OK. There are two goals to each of these problems.The first is to write a balanced chemical equation, and then the second part is to do stoichiometry calculations.

In the first problem, you have sodium metal (Na) reacting with water to form hydrogen gas (H2). I'm guessing that the "rule" has something to do with water forming hydrogen gas and leaving hydroxide ions (OH-). So, the unbalanced equation will be:

Na(s) + H2O --> H2(g) + NaOH But this equation is not balanced. To balance it, you'll need to play around with the coefficients so that both sides have the same numbers of every atom.
In this case, the balanced equation will be:
2 Na + 2 H2O --> H2 + 2 NaOH

Now, to the stoichiometry part. You want to produce 0.540 moles of H2 gas. Since you need 2 moles of Na for every mole of H2, you'll need 2 X 0.540 moles of Na, or 1.080 moles of Na. Using the molar mass of Na, you can convert that to mass, and you'll find that you need 24.8 grams of Na.

Summarizing:
(0.54 mol H2) (2 mol Na/molH2) (23.0 g Na/mol Na)=24.8 g Na.

The rest of the problems are basically the same, and you can solve them in basically the same way.

In the third and fourth problems, you'll convert the mass that you are given into moles, then use the balanced equation to calculate moles of the things asked for, and then convert those into grams.

Answer 2

i really don't like chemistry although i get above 75.
i think you must refers to help books.