C4 Chemical calculations

Question 1

Avogadro constant

Answer 1

the number of atoms, molecules, or ions in a mole of any substance (i.e., 6.02 × 10-23 per mol)

Question 2

burette

Answer 2

a long glass tube with a tap at one end and markings to show volumes of liquid; used to add precisely known volumes of liquids to a solution in a conical flask below it

Question 3

concentration

Answer 3

the amount of a substance dissolved in a given volume of liquid

Question 4

concordant

Answer 4

when you have two titration results that are within 0.1cm3 of each other. These precise results can then be used to calculate an accurate mean

Question 5

end point

Answer 5

the point in a titration where the reaction is complete and titration should stop

Question 6

limiting reactant

Answer 6

the reactant in a chemical reaction that when used up causes the reaction to stop

Question 7

mole

Answer 7

the amount of substance in the relative atomic or formula mass of a substance in grams

Question 8

percentage yield

Answer 8

the actual mass of product collected in a reaction divided by the maximum mass that could have been formed in theory, multiplied by 100

Question 9

pipette

Answer 9

a glass tube used to measure accurate volumes of liquids

Question 10

relative atomic mass Ar

Answer 10

the average mass of the atoms of an element compared with carbon-12 (which is given a mass of exactly 12). The average mass must take into account the proportions of the naturally occurring isotopes of the element

Question 11

relative formula mass Mr

Answer 11

the total of the relative atomic masses, added up in the ratio shown in the chemical formula, of a substance

Question 12

titration

Answer 12

a method for measuring the volumes of two solutions that react together

Question 13

yield

Answer 13

the mass of product that a chemical reaction produces