Matter & Materials and Processing Flashcards
When a substance has melted, are the solid and liquid the same material?
Yes
Is dissolving the same as melting?
No. One material dissolves in another. This may involve a chemical reaction.
Do all solids melt on heating?
No, they may burn or decompose.
What is the name of the solid which dissolves in another?
Solute
What is the name of the liquid a substance dissolves in?
Solvent
Give an example of a solvent.
Water. Solubility is an important property of water.
Give an example of three solutes.
- Sugar
- Salt
- Saltpeter ( potassium nitrate)
When a melted substance re-solidifies does it always return to it’s original form or shape?
No.
What does the combination of a solute and solvent give?
Solution
Are all liquids soluble in water?
No. Oil and paraffin are not soluble in water.
Are all solids soluble in water?
No, solids like sand and sulphur don’t dissolve.
Give example of two liquids that are water-soluble.
Methylated spirits, alcohol.
What do you call a solution in which the solvent can’t dissolve any more solute?
Saturated.
What do you call a solution that continues to dissolve a solute?
Unsaturated
What happens to a hot, saturated solution that is cooled?
Crystals are formed.
What do you call the process of forming crystals?
Crystallisation
Once a solution is formed, how do you separate the solute from the solvent?
Make sure it is saturated and then heat it. Once it cools the solute will form crystals.
What is melting?
When a substance is heat and it changes from a solid to a liquid.
Does stirring make a solute dissolve faster?
Yes, stirring increases the rate of solubility
What happens if a saturated solution of copper sulphate is left to stand for a few days?
The solvent (water) evaporates and the solute (copper sulphate) can be recovered
Give an example of crystallized solutes found in everyday life.
Stalactites and stalagmites
How are stalactites formed in a cave?
- Water mixes with lime from the limestone rock.
- This drips from the ceiling.
- Lime crystallizes from the solution as the water evaporates.
- A stalactite is formed.
Does the size of a solid affect its solubility?
Yes, a finer grained salt dissolves faster than a coarse grain.
Does heating increase the rate of solubility?
Yes. When the solvent is heated, the particles move faster than in a cooler solvent. This allows the solute and solvent to mix quicker.
