Search our library of Chemistry A Level questions

Top answers

Chemistry

A Level

For the following reaction, you obtained 7.2 g of sodium sulfate, starting from 10 g of sulfuric acid. Sodium hydroxide is in excess. What is the % yield? H2SO4 + 2NaOH → Na2SO4 + 2H2O

Identify the limiting reagent: you have been told sodium hydroxide is in excess, so you know sulfuric acid is the limiting reagent
Calculate the moles of the limiting reagent: ...

Answered by Rachel B. • Chemistry tutor

2828 Views

Define relative atomic mass.

Relative atomic mass is the mass of one atom of an element compared to 1/12 of the mass of an atom of carbon-12.

Answered by Colleen S. • Chemistry tutor

2416 Views

Explain why sulfur deviates from the general trend in ionisation energies across period 3.

Sulfur has the electronic structure [Ne]3s2 3p4. This means there are 2 electrons in the same p orbital. These repel each other making it easier to remove the electron causing the ionisation energy to be ...

Answered by Angus M. • Chemistry tutor

11418 Views

Describe the enthalpy change of formation of butane.

The enthalpy change of formation of butane is the enthalpy produced when one mole of butane is formed from its elements, all under standard conditions and in their standard states.

4C_(s)

Answered by Edward L. • Chemistry tutor

13422 Views

Explain the melting points of period 3 elements.

Going from Na to Si, the melting point increases. This is because from Na-Al, the charge of the metal ion and the number of delocalised electrons increases so the strength of the metallic bonding increase...

Answered by Amanpreet K. • Chemistry tutor

5075 Views