| What is meant by saturated solution? | When the solution cannot dissolve no more solute at the temperature. |
| What is an aqueous solution? | A solution of water. |
| What is volatile liquid and what's the reason it is volatile? | A volatile liquid is a liquid that can evaporate easily as a result of its weak bonds(weak forces of attraction). |
| How can you identify an impure substance? | Melting point falls and boiling point rises
It melts and boils over a range of temperatures and not sharply |
| The more the impurity there is... | The bigger the change in in melting and boiling points
The wider the temperature range over which melting and boiling occurs. |
| Filtration is used to separate ... | A solid from a liquid |
| Crystallisation is used to separate... | A solute from its solution |
| Evaporation is used to separate... | A solute from its solution |
| Simple distillation is used to separate ... | A solvent from its solution |
| Simple distillation is used to separate ... | A solvent from its solution |
| Fractional distillation is used to sperate ... | Liquids from each other |
| Chromatography is used to separate... | Different substances from a solution |
| When filtering the trapped solid is called the... and the liquid passed through is called the... | Residue
Filtrate |
| Why does cooling cause crystals to form when using crystallisation? | Since soluble solids are less soluble when temperature is lower, crystals form when temperature is reduced. |
| Give the four steps in the process of crystallisation done in order to separate copper(II) sulfate from water. | 1) The solution is heated to evaporate some of the water to make the solution more concentrated.
2)Eventually the solution becomes saturated, if you cool it now crystals will stat to form.
3) Leave the solution to cool. Crystals start to form in it as the temperature falls.
4) Remove the crystals by filtering, then rinse them with distilled water and dry them with filter paper. |
| What can be done to separate a mixture of salt and sugar? | Water cannot be used since both dissolve in water but Ethanol can dissolve only sugar, so it can be used.( When heating ethanol solution a water bath should be used since ethanol is flammable ). |
| Give the steps to purify water which contains impurities | 1) Heat the solution in the flask. As it boils, water vapour rises into the condenser, leave impurities(salts) behind.
2) The condenser is cold, so the vapor condenses to water in it.
3) The water drips into the beaker. It s called distilled water(it is almost pure) |
| Give the steps to separate a mixture of water and ethanol. | 1) Heat the mixture in a flask. At 78 C the ethanol begins to boil, some water evaporates too. So a mixture of ethanol and water rises up the column.
2) The vapour condenses on the glass beads in the column making the beads hot.
3)When the beads reach about 78 C ethanol vapour can no longer condense on them, only the water vapour does. So the water drips into the flask, the ethanol goes into the condenser where it condenses and pure ethanol drips into the beaker.
4)Eventually, the thermometer reading rises above 78 C, a sign that all the ethanol has gone. |
| Name two places where fractional distillation is industrially used. | Refining crude oil
Separate the gases in air. |
| How does solubility of a substance affect of how far it will travel in the chromatography paper? | More the soluble a substance is in a solvent the further it will travel up the chromatography paper. |
| What is locating agent used for? | Used to show up the colorless substances in chromatography, by reacting with them to form colored substances |
| How do you calculate the Rf value? | Distance moved by solute divided by the distance travelled by the solvent. |
