Consider the following reaction:

Zn (s) + 2HCl (aq) ---> ZnCl2 (g) + H2 (g)

If the reaction has a 68.4% yield, how many grams of zinc are needed to obtain an actual yield of 1.00 g of zinc chloride?

Stuck on how to figure this out!

Zn = 65.4 grams/mol

Cl = 35.5 grams/mol
H = 1 gram/mol

so
2HCl = 2(36.5g/mol) = 73 g
ZnCl2 = 136.4 g/mol

to get 1 gram ZnCl2 need
(1/.684)(65.4/136.4)= .701 grams Zn

To solve this problem, we can use stoichiometry and the concept of percent yield. Here are the steps to follow:

Step 1: Write the balanced chemical equation.
Given: Zn (s) + 2HCl (aq) ---> ZnCl2 (g) + H2 (g)

Step 2: Determine the molar mass of ZnCl2.
The molar mass of ZnCl2 can be calculated by adding up the atomic masses of zinc (Zn) and two chlorine (Cl) atoms. By consulting the periodic table, we find that the atomic mass of Zn is 65.38 g/mol, and the atomic mass of Cl is 35.45 g/mol. Therefore, the molar mass of ZnCl2 is 65.38 + (2 * 35.45) = 136.28 g/mol.

Step 3: Calculate the theoretical yield of ZnCl2.
The theoretical yield is the maximum amount of product we can obtain according to the balanced equation. Use stoichiometry to determine this value by considering the molar ratio between Zn and ZnCl2. From the balanced equation, we know that 1 mole of Zn reacts to produce 1 mole of ZnCl2. Thus, the theoretical yield of ZnCl2 is equal to the mass of Zn used.

Step 4: Calculate the mass of Zn needed.
To find the mass of Zn needed, we need to rearrange the equation for theoretical yield and solve for the mass of Zn. Given that the theoretical yield of ZnCl2 is equal to the mass of Zn used, we can set up the following equation:

Theoretical yield of ZnCl2 (g) = Mass of Zn (g)

Step 5: Apply the percent yield.
The percent yield is given as 68.4%, which means that the actual yield is 68.4% of the theoretical yield. Mathematically, the actual yield (in grams) is calculated by multiplying the theoretical yield by the percent yield:

Actual yield of ZnCl2 (g) = (Percent yield / 100) * Theoretical yield of ZnCl2

Given that the actual yield of ZnCl2 is 1.00 g and the percent yield is 68.4%, we can rearrange the equation to find the theoretical yield:

Theoretical yield of ZnCl2 = Actual yield of ZnCl2 (g) * (100 / Percent yield)

Step 6: Calculate the mass of Zn needed.
Since the theoretical yield is equal to the mass of Zn, the mass of Zn needed to obtain an actual yield of 1.00 g of ZnCl2 is equal to the theoretical yield calculated in step 5.

Finally, you can use the molar mass of Zn to convert the result from moles to grams, if necessary.