Chemistry: Changing materials (7abcdefgh) Flashcards
What is dissolving?
When a solute enters a solvent and becomes a solution.
What tends to happen to the solubility of solutes as the temperature increases?
It increases, dissolves quicker and easier at higher temperatures.
If I put 5g of sugar in 20g of water what would the total mass be?
25g, mass is conserved. All particles are still there even though you can no longer see them.
What do you use to test for water vapour / moisture in the air?
Anhydrous copper sulphate (turns white to blue with moisture) or anhydrous cobalt chloride (blue to pink)
Other than water, name two other solvents often used.
Ethanol and propanone.
What flame is present on a Bunsen Burner with the air hole closed?
Safety flame
Why is a safety flame cooler than a roaring flame?
It doesn’t have enough oxygen so the gas doesn’t burn fully ( incomplete combustion), hence the yellow flame.
What colour flame is seen when methane or propane gas is burning fully?
Blue
What is the hottest part of a roaring flame?
Top of the pale blue inner cone.
When things burn in air what element do they react with?
Oxygen
What is formed when carbon burns fully?
Carbon dioxide
What is formed when carbon undergoes incomplete combustion (doesn’t burn fully)?
Carbon monoxide (CO)
Fossil fuels can contain sulphur, what problems does this cause when they burn?
Sulphur dioxide (acidic) can be formed, this can lead to acid rain when is dissolved into rain.
Carbon dioxide produced in combustion can also cause problems, why?
It is a greenhouse gas and so can trap the heat from the sun, many scientists believe this leads to global warming.
