4.3 quantitive chemistry 0.0 / 5 ? ChemistryCalculations, moles and yieldGCSEAQA Created by: elfassiyaseen23Created on: 20-09-20 13:11 Q) What is the law of conservation of mass? A) No atoms are lost or made during a chemical reaction so the mass of the products equals the mass of the reactants. . 1 of 14 Q) Balance this word equation: Calcium oxide + Hydrochloric acid -> Calcium chloride + Water A) CaO + 2 HCl -> CaCl2 + H2O 2 of 14 Q) How do you calculate “Relative formula mass”? A) RFM is the sum of the relative atomic masses of all the atoms in the compound 3 of 14 Q) What should you notice with the total relative formula mass of the reactants and the total relative formula mass of the products? A) The total RFM of all the reactants is equal to the total RFM of the products 4 of 14 Q) Why could the conservation of mass not be noticed when a gas is produced? A) The mass of the products appearing to be less because the gas was released. 5 of 14 Q) What is the unit of amount of a substance? A) Chemical amounts are measured in moles and the symbol is mol. 6 of 14 Q) What mass of a substance is “one mole”? A) The mass of one mole of a substance is the same as the relative formula mass in grams 7 of 14 Q) How many particles does “one mole” contain? A) - One mole of any substance contains the same number of particles which is 6.02x1023. This is Avogadro’s constant 8 of 14 Q) How can we calculate unknown masses of reactants and products? A) The masses of reactants and products can be calculated from balanced symbol equations 9 of 14 Q) What does the “2” represent in 2HCI? A) The number of moles of used or produced in a reaction otherwise known as “Reaction stoichiometry” 10 of 14 Q) Mg + 2HCI -> MgCI2 + H2: How many moles needed of Mg to react with HCL? A) One mole of magnesium has reacted with two moles of hydrochloric acid to make one mole of magnesium chloride and one mole of hydrogen gas. 11 of 14 Q) What is a limiting reagent? A) A reactant not in excess is a limiting reagent. This decides how much product can be produced. 12 of 14 Q) What is “Concentration of a solution”? A) The amount of a chemical that is dissolved in water 13 of 14 Q) What are the units for concentration? A) g/dm3 or mol/dm3 14 of 14
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