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(a) When a 2.00-g strip of zinc metal is placed in an aqueous solution containing

2.50g of silver nitrate, the reaction is

Zn(s) + 2AgNO3 (aq) →2Ag(s) + Zn (NO3)2(aq)

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Mass of zinc (Zn): 2.00 g

Mass of silver nitrate (AgNO3): 2.50 g

Molar masses:

Molar mass of Zn: ~65.38 g/mol

Molar mass of AgNO3: ~169.87 g/mol

Molar mass of Ag: ~107.87 g/mol

Molar mass of Zn(NO3)2: ~189.39 g/mol

(a) To determine the limiting reactant, we need to compare the moles of each reactant and see which one produces the smallest amount of the product. The balanced equation tells us that 1 mole of Zn reacts with 2 moles of AgNO3.

Moles of Zn = Mass of Zn / Molar mass of Zn = 2.00 g / 65.38 g/mol ≈ 0.0306 mol

Moles of AgNO3 = Mass of AgNO3 / Molar mass of AgNO3 = 2.50 g / 169.87 g/mol ≈ 0.0147 mol

Since the stoichiometric ratio is 1:2 for Zn and AgNO3, and the moles of AgNO3 are less than half the moles of Zn, AgNO3 is the limiting reactant.

(b) The balanced equation indicates that 1 mole of Zn produces 2 moles of Ag. Since the limiting reactant is AgNO3, which has 0.0147 mol, the number of moles of Ag formed is:

Moles of Ag = Moles of AgNO3 × (2 moles of Ag / 2 moles of AgNO3) = 0.0147 mol × 1 = 0.0147 mol

Mass of Ag formed = Moles of Ag × Molar mass of Ag = 0.0147 mol × 107.87 g/mol ≈ 1.585 g

(c) Since 1 mole of Zn(NO3)2 is produced for every mole of Zn reacting, and the moles of Zn are 0.0306 mol, the moles of Zn(NO3)2 formed will also be 0.0306 mol.

Mass of Zn(NO3)2 formed = Moles of Zn(NO3)2 × Molar mass of Zn(NO3)2 = 0.0306 mol × 189.39 g/mol ≈ 5.80 g

(d) To find the grams of the excess reactant left at the end of the reaction, we need to calculate how many moles of AgNO3 would be required to fully react with the available moles of Zn (0.0306 mol):

Moles of AgNO3 required = Moles of Zn × (2 moles of AgNO3 / 1 mole of Zn) = 0.0306 mol × 2 = 0.0612 mol

Excess moles of AgNO3 = Moles of AgNO3 initially - Moles of AgNO3 required = 0.0147 mol - 0.0612 mol = -0.0465 mol (negative because it's in excess)

Since we have negative moles of AgNO3, this means there is no excess AgNO3 left at the end of the reaction.

In summary:

(a) The limiting reactant is AgNO3.

(b) The mass of Ag formed is approximately 1.585 g.

(c) The mass of Zn(NO3)2 formed is approximately 5.80 g.

(d) There is no excess AgNO3 left at the end of the reaction.

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