Amount Of Substance

Question 1

Acid + Base -> ?

Answer 1

Salt + water

Question 2

Acid + carbonate-> ?

Answer 2

Salt + water + carbon dioxide

Question 3

Ionic equation for neutralisation (acid and base)

Answer 3

H+(aq) + OH-(aq) -> H2O (l)

Question 4

Ionic equation for neutralisation (acid and carbonate)

Answer 4

2H+(aq) + CO3 2-(aq) -> H2O (l) + CO2 (g)

Question 5

Ionic equation for neutralisation (acid and hydrogencarbonate)

Answer 5

H+(aq) + HCO3-(aq) -> H2O (l) + CO2 (g)

Question 6

Ionic equation for neutralisation (acid and ammonia)

Answer 6

H+(aq) + NH3(aq) -> NH4+(aq) compound

Question 7

How does water dissolve ionic substances

Answer 7

There is a bond between the water molecules and ions that can be stronger than the actual ionic bonds in the lattice. So te ion is taken away.

Question 8

Spectator ions

Answer 8

The ions that are not involved in a reaction involving ionic compounds dissolved in water.

Question 9

Mass and moles formula

Answer 9

Moles = Mass(g) / Mr

Question 10

Moles and concentration formula

Answer 10

No. of moles = conc(mol/dm3) X vol(dm3)

Question 11

Ideal gas law

Answer 11

PV=nRT
P(pa)
V(m3)
n(moles)
R(8.31)
T(K)

Question 12

Assumptions made in the ideal gas law

Answer 12

Molecules/atoms: occupy negligible volume, exert no force on each other (all collisions are completely elastic), don’t react when they collide.

Question 13

Limiting reagent

Answer 13

The reactant that is not in excess.

Question 14

%yield formula

Answer 14

(mass of product/max theoretical mass) X 100

Question 15

Atom economy equation

Answer 15

(mass of wanted product/total mass of products) X 100

Question 16

Empirical formula

Answer 16

The simplest whole number ratio of the atoms of each element in a substance.

Question 17

Finding the molecular formula from the empirical formula

Answer 17

Divide real Mr by the empirical Mr and multiply the numbers of each element in the empirical formula by this number.

Question 18

What affects %yield?

Answer 18

If the reaction is reversible, if the product is lost when isolating it from the reaction mixture, unwanted reactions may occur.

Question 19

How to prepare a stock solution

Answer 19

Record the mass of a clean dry weighing boat. Measure the approximate mass of the sample. Find the mass of the sample on a high precision balance. Wash the contents of the weighing boat into a volumetric flask (250cm^3) using deionised water and a clean funnel. Add more deionised water nearly up to the mark. Shake well to dissolve. Make to the mark using a dropping pipette and shake well.

Question 20

Difference between atom economy and %yield

Answer 20

Atom economy tells us in theory how many atoms must be wasted in a reaction. The yield tells us about the practical efficiency of the process and how much product is lost due to its lack of efficiency.

Question 21

What is a mole?

Answer 21

A quantity of a substance that contains the Avogadro number of particles (atoms, molecules, or ions)

Question 22

How to carry out a titration

Answer 22

Pour some of the stock solution into a beaker to prevent the possibility of contamination of the rest of the solution. Use a pipette and pipette filler to accurately measure out a specific volume. Empty into a conical flask and add 3drops of methyl orange. Rinse some of the acid you will use through the tap of a burette and clamp it vertically to a stand. Fill it to near the 0 mark. Put the flask on a white tile under this and allow the acid through the tap until the solution turns permanently red. Record the amount of acid used. Repeat, adding acid slowly when near the previous amount used. Repeat until concordant results (0.1cm^3).

Question 23

Which titres do you use for the mean?

Answer 23

Only the concordant ones.

Question 24

Units of gas constant R

Answer 24

J/K/mol