How many grams of hydrochloric acid will react completely with a block of gold is 3.2 cm by 3.8 cm by 2.8 cm, if the density of gold is 19.3 g/mL? Show all steps of your calculation as well as the final answer.
Explanation: 1- we will get the mass of the reacting gold: volume of gold = length * width * height volume of gold = 3.2 * 3.8 * 2.8 = 34.048 cm^3 = 34.048 ml density = mass / volume Therefore: mass = density * volume mass of gold = 19.3 * 34.048 = 657.1264 grams
2- we will get the number of moles of the reacting gold: number of moles = mass / molar mass number of moles = 657.1264 / 196.96657 number of moles = 3.3362 moles
3- we will get the number of moles of the HCl: First, we will balanced the given equation. The balanced equation will be as follows: Au + 2HCl ......> AuCl2 + H2 This means that one mole of Au reacts with 2 moles of HCl. Therefore 3.3362 moles will react with 2*3.3362 = 6.6724 moles of HCL
4- we will get the mass of the HCl: From the periodic table: molar mass of H = 1 gram molar mass of Cl = 35.5 grams Therefore: molar mass of HCl = 1 + 35.5 = 36.5 grams/mole number of moles = mass / molar mass Therefore: mass = number of moles * molar mass mass of HCl = 6.6724 * 36.5 mass of HCl = 243.5426 grams
