Atoms/ Bonding
What is the charge and the mass of proton?
Charge: positive
Mass: 1
Which states of matter can be copressed easily. Why?
Gas.
There are spaces between particles.
Calculate RFM of Ca(OH)2
74
What does filtration separates?
What do we call what is left on the filter paper, collected in the beaker?
To separate insoluble solute from the mixture.
Residue
Filtrate
What is the difference between acid and alkali?
Acid - produce hydrogen ions, pH below 7.
Alkali - produce hydroxide ions, pH above 7.
What is electron configuration of Magnesium.
2.8.2
Which state change/(s) requires energy to be absorbed?
Condensation
Freezing
Calculate the percentage by mass of magnesium in MgO.
(24/ 40) x100 = 60%
Explain why different dyes travel different distances during chromatography.
More soluble substance dissolves quicker and travels further.
What does it mean concentrated and diluted acid?
Concentrated - a lot of acid, little water.
Diluted - little acid, a lot of water.
How many electrons, protons and neutrons Calcium ion has.
Ca2+
Protons: 20
Electrons: 18
Neutrons: 20
Melting point of A is -50C.
Boiling point of A is 80C.
Predicting its state at -5C, 0C, 90C.
-5: Liquid
0: Liquid
90: Gas
How many moles are in 150g of CaCO3.
Include units.
RFM (CaCO3)= 100
moles= 150/100= 1.5mol
Explain distillation.
What are 2 processes included in distillation?
To separate liquids using their different boiling points.
Evaporation
Condensation
Explain why pH changes during neutralisation.
Hydrogen ions react with hydroxide ions to form water.
As hydrogen ions are neutralised, the solution becomes less acidic and the pH increases.
Explain why ionic compounds have high melting points.
Think about: forces, energy required.
There are strong electrostatic forces between ions.
This requires a lot of energy to break.
Why are melting and boiling points considered physical properties?
2 things to mention
It is reversible.
No new product is made.
What does the law of conservation of mass state?
During the experiment, the mass decreased by 3g. Give possible explanation that do not break the law of conservation of mass.
A gas escaped from the opened container.
Some reactants or products were lost during experiment (splashed out of the beaker).
Explain what are dependent, independent and control variables.
Identify those variables: How temperature affects the time taken for copper sulphate crystals to form.
Independent - what is changed (temperature)
Dependent - what is measured (time)
Control - kept the same (Volume of acid, mass of alkali and etc)
Explain why heating should stop before all the water has been evaporated during crystalisation.
To form large crystals.
Atoms have space to move and form lattice structure.
Identify type of bonding in H2O.
Draw dot and cross diagram.
Covalent bonding
A 9B1 student wants to know if a white powder is pure. Explain how melting point could help.
If white powder melts at fixed temperature - it is pure.
If it has a range - impure sample.
A compound contains 56g of iron (Fe) and 48g of oxygen (O). Determine the empirical formula.
Show your working out.
FeO3
A mixture contains ethanol, water, dissolved salt and sand. Explain in order, how would you obtain all four substances as pure samples.
Filtration (to separate sand)
Distillation (to separate ethanol, lower boiling point)
Evaporation/ crystallisation (to evaporate water and collect salt)
Explain why filtration is essential before crystallisation when using insoluble base for copper sulphate crystals.
To remove an excess base, which has not reacted with sulphuric acid.