Common Mistakes Flashcards
What is meant by molar mass
Mass of one mole of a compound
Number of protons, neutrons and electrons in 18, 8 O2-
8 p
10 n
10 e
State the difference, if any, between the chemical properties of the isotopes 6Li and 7Li, giving a reason for your answer.
There would be no difference as there is the same number of electrons in the outer shell
Why is the Ostwald process carried out at a temperature of around 900 degrees celcius
It is a compromise temperature between high yield and high rate
A temperature too low - slow reaction
A temperature too high - too low yield
Explain why there has been much research to find a better catalysts
As less temperature is needed
Increased yield
Faster equilibrium is reached
State one example of an industrially or environmentally important heterogenous catalyst. Identify the reaction catalysed and name the catalyst
Iron in the Haber Process for the production of ammonia
Ionic equation between silver and chlorine
Ag+ + Cl- —> AgCl
Potassium is ignited and put in a jar with oxygen to form potassium oxide
State what can be seen as the reaction proceeds
- lilac flame
- potassium melts
- white solid forms
State whether you would expect rubidium to be more reactive or less reactive than potassium.
Give a reason for your answer
More reactive
Group 1 elements become more reactive down the group due to the electron being more easily lost as there is decreasing ionisation energy
A student added 2.0 g of calcium to some water and collected the hydrogen gas formed.
The student repeated the reaction using the same mass of barium.
He noticed that the volume of gas, still at the same temperature and pressure, was less. Why?
Less moles of barium used as barium has a higher atomic mass
Why are halogens oxidising agents?
They gain one electron to complete the outer shell
They take the electron from another species
State, giving a reason, which halogen is the strongest oxidising agent
Fluorine
Greatest electron affinity
Least electron shielding
Greatest effective nuclear charge
Give the physical states of chlorine and iodine at room temperature
Chlorine is gas
Iodine is solid
State what is observed (if anything) when chlorine and iodine are added separately to potassium bromide solution.
Write an equation for any reaction.
Chlorine - solution turns from colourless to orange/brown
Cl2 + 2Br- —> 2Cl- + Br
Iodine - no change no reaction
Marged adds a strip of magnesium to dilute hydrochloric acid
State what she would observe as this reaction proceeds
Stream of bubbles or effervescence as hydrogen is produced
Magnesium disappears
Heat is given off
