Practicals (Paper 1) Flashcards
What would be seen when a group one metal reacts with water?
Vigorous reaction and fizzing (gas produced)
What is a risk?
The chance that someone or something will be harmed if exposed to a hazard
Describe an experiment to determine empirical formula
- Weigh a crucible with its lid
- Put the magnesium ribbon into the crucible and weigh it again - calculate the mass of magnesium from this (mass of crucible and magnesium - mass of crucible)
- Strongly heat the crucible over a bunsen burner for several minutes
- Carefully lift the lid from time to time to allow sufficient air into the crucible for the magnesium to fully oxidise without letting any magnesium oxide escape
- Heat until the reaction is complete
- Measure the mass of the crucible and its contents after heating and subtract the mass of the crucible to find the mass of the magnesium oxide
- To find the mass of the oxygen, subtract the mass of the magnesium from the magnesium oxide
- Divide the masses by the relative atomic masses of the elements and simplify the ratio
What is the method used to obtain salts from insoluble bases?
- Measure out 25cm cubed of sulfuric acid and pour into a beaker
- Add an excess amount of copper oxide
- Warm in a water bath to make sure reaction is complete
- Filter out any excess base using filter paper and a funnel
- Pour solution into and evaporating basin and heat gently to evaporate the water, pure dry copper sulfate crystals will be formed
What is the method for distillation?
- The ethanol/water mixture is heated the mixture starts to boil and hot vapour starts to rise up the fractionating column, the vapour condeses as it hits the cool surface and drips back down
- The fraction with the lowest boiling point reaches the top of the column first and its vapour passes into the condenser and then drips into a beaker
- If you keep heating, vapours from fractions with lower boiling points will rise up the column and pass into the condenser
What is the method for crystallisation?
- The solution is heated to remove enough solvent to produce a saturated solution
- The saturated solution is allowed to cool
- Crystals form in the solution, the crystals are separated from the solution using filtration and they’re then dried using a drying oven
What is the method for chromotography?
- Draw a pencil line near the bottom of the chromotography paper and place small spots of different mixtures on the line
- Place this paper in a beaker with water in it that doesn’t go above the pencil line
- Allow the solvent to travel through the paper and measure the distance from the pencil line to the solvent front and the centre of each spot
- Calculate the Rf value of each spot
What is the test for hydrogen gas?
A lighted splint placed into the test tube that possibly contains hydrogen, a squeaky pop is made if hydrogen is present
What is the test for carbon dioxide?
Gas is added to limewater turns and it turns cloudy if carbon dioxide is present
What is the method for carrying out a neutralisation reaction?
- Add dilute hydrochloric acid to a beaker and measure and record the pH
- Add a small mass of calcium hydroxide power to the acid and stir, then measure and record the pH again
- Repeat until the pH no longer changes
What is the method for electrolysis of copper sulfate (using copper electrodes)?
- Connect two copper electrodes to a power pack using wires
- Put the electrodes in the copper sulfate solution
- Switch on the power pack and observe what happens
What is the method for carrying out an accurate acid-alkali titration?
- Put dilute hydrochloric acid into the burette
- Use a pipette to add 25cm^3 of sodium hydroxide solution to the conical flask and then add a small amount of indicator
- Put the flask on a white tile beneath the burette
- Record the burette start reading
- Add acid until the indicator stops changing colour
- Record the burette end reading
- Calculate the titre (end reading - start reading)
- Repeat the previous steps until concordant titres are achieved
What is the reaction for rusting?
iron + oxygen + water → hydrated iron (III) oxide
What is the method for deducing a reactivity series?
- Add a powdered metal to a test tube of metal salt solution and look for evidence of a reaction. For example a change in colour or temperature
When you’re trying to determine what volume of alkali is required to neutralise an known volume of acid, do you use a known volume of acid or alkali?
Acid
