PAPER 2 unknown things Flashcards
List two properties of alkali metals.
- Soft
- Relatively low melting point
What’s observed when Lithium reacts in water?
- Gentle bubbling
- Does not melt
What’s observed when Sodium reacts in water?
- Floats on water
- More bubbling, causing the metal to move around on the surface of the water
- The sodium melts
What’s observed when Potassium reacts in water?
- Melts into a shiny ball
- Violent bubbling
- Moves rapidly across the surface of the water
- Burns with a lilac flame
What is the colour and state of chlorine at room temperature?
Pale green gas
What is the colour and state of bromine at room temperature?
Red-brown liquid
What is the colour and state of iodine at room temperature?
Black solid
What’s the chemical test for chlorine gas?
Place damp litmus paper into a test tube of the gas. If the paper turns red then white, chlorine is present due to its bleaching effect.
What are the colours of the different halide solutions?
Chlorine - colourless
Bromine - orange
Iodine - brown
How can rate of reaction be measured when a precipitate is formed?
Place a black cross beneath the beaker. Measure the amount of time until the cross can no longer be seen. This is inaccurate however as this can be subjective.
What is the equation for anaerobic respiration in plants?
Glucose -> ethanol + CO2
What fraction of crude oil is used for surfacing roads?
Bitumen
What type of reaction is cracking?
Thermal decomposition
What is the current composition of the Earth’s atmosphere?
Nitrogen: 78%
Oxygen: 21%
Argon: 0.93%
Carbon dioxide: 0.04%
How do you test for aqueous metal ions?
Add sodium hydroxide to the solution.