C5.1 Monitoring chemical reactions

Question 1

accurate

Answer 1

a measure of how close a result is to the true value. An accurate result is very close

Question 2

actual yield

Answer 2

the mass of product obtained in a chemical reaction

Question 3

atom economy

Answer 3

proportion of atoms in the reactants that end up in the desired product. It is given by (sum of Mr of desired product ÷ sum of Mr of all products) × 100

Question 4

burette

Answer 4

a graduated tube with a tap, used in titrations

Question 5

by-product

Answer 5

a substance formed in a reaction in addition to the desired product. By-products may or may not be useful

Question 6

concordant titres

Answer 6

results from a titration that are within 0.10cm3 of each other

Question 7

end-point

Answer 7

the point at which the two reactants in a titration have exactly reacted together

Question 8

limiting reactant

Answer 8

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

Question 9

measuring cylinder

Answer 9

a piece of apparatus used to measure different volumes of solution

Question 10

meniscus

Answer 10

the curve in the surface of a liquid

Question 11

molar volume

Answer 11

the volume occupied by one mole of a gas (24dm3 at room temperature and pressure)

Question 12

percentage yield

Answer 12

the proportion of the theoretical yield actually obtained during a reaction, expressed as a percentage. It is given by (actual yield ÷ theoretical yield) × 100

Question 13

pipette filler

Answer 13

device to draw liquids into a pipette safely

Question 14

precision

Answer 14

a measure of how close the agreement is between measured values

Question 15

reaction pathway

Answer 15

a reaction, or series of reactions, chosen for making a particular substance

Question 16

repeatable

Answer 16

a measure of how close values are to each other when an experiment is repeated with the same equipment

Question 17

reversible reaction

Answer 17

chemical reaction that can proceed in either direction

Question 18

theoretical yield

Answer 18

the maximum possible mass of product that could be formed in a reaction, calculated using the law of conservation of mass

Question 19

titration

Answer 19

a method in which a neutralisation reaction is used to determine the concentration of an acid or alkali

Question 20

titre

Answer 20

a measured volume of solution added from a burette during a titration to reach the end-point

Question 21

volumetric pipette

Answer 21

a piece of glassware used to measure an accurate volume of solution for a titration

Question 22

yield

Answer 22

the mass of a particular product formed in a reaction