Chemistry (Topics 1-4) Flashcards
(23 cards)
Give one observation a student could make to show that the copper carbonate is in excess when adding it into a beaker of sulfuric acid.
The copper carbonate powder remains in the mixture.
Give one reason for filtering the sulfuric acid and copper carbonate mixture when producing a salt.
To remove the copper carbonate.
Name the equipment that can be used to warm the filtrate gently to allow the copper sulfate crystals to start to form.
Water Bath (NOT bunsen burner)
What is the equation for finding the percentage yield of a product?
% yield = actual/theoretical x 100
Some salts can be produced by reacting sulfuric acid with a metal.
Neither copper nor sodium is used to produce a salt with sulfuric acid.
Give one reason for each metal as to why it’s not used.
Copper:
It does not react with sulfuric acid since it is unreactive, because it is below hydrogen in the reactivity series.
Sodium:
The reaction could to lead to an explosion taking place.
Group 1 elements react with water.
Give two observations made when potassium reacts with water.
Effervescence
Floats Around
Potassium hydroxide solution is produced when potassium reacts with water.
What is the colour of universal indicator when added to potassium hydroxide solution?
Give one reason for your answer.
It will be purple, because the solution is alkaline, and therefore has a high pH.
Which of the following describes the trends going down Group 7?
- Relative molecular mass decreases and boiling point decreases.
- Relative molecular mass decreases and boiling point increases.
- Relative molecular mass increases and boiling point decreases.
- Relative molecular mass increases and boiling point increases.
Option 4
As you go down Group 7 in the periodic table:
Relative molecular mass increases – The atoms get larger and heavier from fluorine (F₂) to iodine (I₂), so the molecular mass increases.
Boiling point increases – As the molecules get bigger, there are stronger intermolecular forces, so more energy (higher temperature) is needed to boil them.
Compare the Plum Pudding Model with the model of the atom used today.
Similarities:
- both contain electrons
- both are neutral overall
Differences:
- PPM has no nucleus.
- PPM has no protons.
- PPM has no neutrons.
- PPM is a ball of positive charge.
- PPM’s electrons are not at fixed distances.
- PPM does not have empty space.
Complete the following ionic equation:
Zn(s) + Cu^2+(aq) -> _______________
Zn(s) + Cu^2+(aq) -> Zn^2+(aq) + Cu(s)
Calcium chloride is an ionic compound.
Calcium and chlorine react to produce calcium chloride.
Describe what happens to calcium atoms and chlorine atoms when the ionic compound calcium chloride is formed.
Calcium atoms lose two electrons, and chlorine atoms gain one electron. Therefore, one calcium atom reacts with two chlorine atoms to form calcium ions and chloride ions.
Iron is a metal.
Describe how iron conducts thermal energy.
Metals are good conductors of thermal energy because energy is transferred by the delocalised electrons.
Pure iron is too soft for many uses.
Explain why mixing iron with other metals makes alloys which are harder than pure iron.
Alloys are harder materials than pure metals because the different sizes of atoms distort the layers of atoms. This makes it more difficult for them to slide over each other.
When iron reacts with chlorine, 0.12 mol of iron reacts with 0.18 mol of chlorine (Cl2).
Which is the correct equation for the reaction?
Fe + Cl → FeCl
Fe + 3Cl2 → FeCl
2Fe + Cl → 2 FeCl
2Fe + 3Cl2 → 2FeClз
2Fe + 3Cl2 → 2FeClз
Whatis the ratio of the numbers of ions in Fe3O4?
2 Fe2+: 1 Fe3t: 4 O2-
1 Fe2+: 2 Fe3+: 4 O2-
3 Fe2+: 4 O2-
3 Fe3+: 4 O2-
1 Fe2+: 2 Fe3+: 4 O2-
Explain why propane has a low boiling point.
Propane is a simple molecule, so the intermolecular forces are weak, and so require little energy to overcome, and so, hence, they have a low boiling point.
What is meant by a weak acid?
Weak acids partially ionise in aqueous solutions, which means only some of the acid molecules break up into their ions.
Explain what happens to the pH of an acid as the acid is diluted with water.
When an acid is diluted with water, its pH increases, because adding water reduces the concentration of hydrogen ions (H⁺) in the solution.
A student does a titration to find the volume of acid needed to neutralise an alkali.
The student fills a burette with the acid.
Give three more steps the student must do before adding the acid to the alkali from the burette.
You should name any equipment used.
- Use a pipette to add the alkali.
- Add an indicator to the alkali.
- Place a white tile under the conical flask.
A calcium atom is larger than a magnesium atom.
Explain why calcium reacts more vigorously than magnesium with hydrochloric acid of the same concentration.
Calcium has more electron shells than magnesium, so its outer electrons are further from the nucleus.
This increased distance and greater shielding from the inner electron shells weakens the attraction between the nucleus and the outer electrons.
Calcium then loses its outer electrons more easily, forming Ca²⁺ ions faster.
This increases the reaction rate with acid, producing hydrogen gas more vigorously.
Give one reason for random errors in an experiment.
The stirring may not be consistent.
Fe2Oз reacts with carbon to produce carbon dioxide.
The equation for the reaction is: 2 Fe2O3(s) + 3C(s) → 4 Fe(s) + 3 CO2(g)
Calculate the volume of carbon dioxide gas at room temperature and pressure that is produced from 40.0 kg of Fe2O3 using excess carbon.
Relative formula mass (Mr): Fe2O3 = 160
The volume of 1 mole of any gas at room temperature and pressure is 24 dm3.
40kg = 40,000g
moles of Fe2O3 = 40,000/Mr = 40,000/160 = 250
Co2 : Fe2O3 = 3:2
moles of CO2 = 250 x 3/2 = 375
volume of CO2 = 375 x 24 = 9000 dm^3
The student titrated a solution containing 0.0045 moles of sodium hydroxide with 0.15 mol/dm3 hydrochloric acid.
The equation for the reaction is: NaOH + HCl → NaCl + H2O
Calculate the volume of hydrochloric acid in cm3 needed in the titration.
Volume in dm3 = 0.0045 / 0.15 = 0.03 dm3
0.03 dm3 = 0.03 x 1000 = 30 cm3
