How many grams of hydrochloric acid are required to react completely with 4.30 grams of zinc? I got 4.80g HCl for the answer but do not know how to do part 2 which is, How many molecules of a gas will be produced?
Thanks.
How did you do the HCl part? Something like this?
mols Zn = g/molar mass = 4.30/65.37 = 0.06578
Then convert mols Zn to mols HCl using the coefficients in the balanced equation.
mols HCl = 0.06578 x(2 mols HCl/1 mol Zn) = 0.06578 x 2 = 0.1316
Then convert mols HCl to grams. mols x molar mass = g = 0.1316 x 36.5 = 4.80 g HCl required.
Now we do the same thing for mols H2.
mols Zn = 4.30/65.37 = 0.06578
Convert to mols H2 gas.
0.06578 mols Zn x (1 mol H2/1 mol Zn) = 0.06578 mols H2.
How many molecules. We know there are 6.02 x 10^23 molecules in a mol. Therefore,
molecules = 0.06578 mols H2 x (6.02 x 10^23 molecules/1 mol) = ??
I hope this helps.
Check my work carefully.
To determine the number of grams of hydrochloric acid (HCl) required to react completely with zinc (Zn), we need to use the balanced chemical equation for the reaction:
Zn + 2HCl -> ZnCl2 + H2
From this equation, we can see that for every 1 mole of Zn, we need 2 moles of HCl to completely react. To find the number of moles of Zn, we divide the given mass (4.30 grams) by the molar mass of Zn (65.38 grams/mol):
Moles of Zn = 4.30 g / 65.38 g/mol ≈ 0.066 mol (rounded to 3 decimal places)
Since the reaction requires a 1:2 ratio between Zn and HCl, the number of moles of HCl needed will be twice the number of moles of Zn:
Moles of HCl = 0.066 mol of Zn × 2 = 0.132 mol
To convert the number of moles of HCl to grams, we need to multiply by the molar mass of HCl (36.46 grams/mol):
Mass of HCl = 0.132 mol × 36.46 g/mol ≈ 4.808 g (rounded to 3 decimal places)
Therefore, the correct answer for the first part is indeed 4.808 grams of HCl, not 4.80 grams.
Now, let's proceed to the second part of your question. To determine the number of molecules of gas (H2) produced, we need to use Avogadro's number and the balanced chemical equation.
From the balanced chemical equation, we can see that for every 1 mole of H2 ,we need 2 moles of HCl. So, the number of moles of H2 produced will be the same as the number of moles of HCl used in the reaction (0.132 mol).
To calculate the number of molecules, we multiply the moles of H2 by Avogadro's number, which is approximately 6.022 × 10^23 molecules/mol:
Number of molecules of H2 = 0.132 mol × 6.022 × 10^23 molecules/mol
Calculating this value gives us:
Number of molecules of H2 ≈ 7.94 × 10^22 molecules
Therefore, approximately 7.94 × 10^22 molecules of H2 gas will be produced.