C3.1 Introducing chemical reactions

Question 1

Avogadro constant

Answer 1

the number of entities in one mole, equal to the number of atoms in 12.0 g of 12C atoms, 6.02 × 1023

Question 2

balanced equation

Answer 2

a model for a reaction showing formulae and number of units for all substances involved. The numbers of each atom are the same on both sides of the equation

Question 3

closed system

Answer 3

apparatus in which substances cannot enter or leave the reaction mixture during a reaction

Question 4

compound ion

Answer 4

an ion formed when a group of atoms loses of gains electrons

Question 5

diatomic molecule

Answer 5

molecule containing two atoms

Question 6

excess

Answer 6

when a reactant is present in an amount greater than that needed to react with the other reactant

Question 7

half equation

Answer 7

a type of chemical equation that models the change that happens to one reactant in a reaction

Question 8

ionic equation

Answer 8

a type of chemical equation that models how oppositely charged ions form an ionic compound

Question 9

law of conservation of mass

Answer 9

the principle that states that the total mass stays the same during a chemical reaction, because atoms are not created or destroyed during a chemical reaction

Question 10

limiting reactant

Answer 10

a reactant present in an amount less that that needed to react completely with the other reactant in a chemical reaction

Question 11

molar mass

Answer 11

the mass in grams of one mole of a substance

Question 12

mole

Answer 12

amount of substance that contains the same number of particles (6.02 × 1023) as there are atoms in 12.0 g of 12C