Chemistry Flashcards Part 2
What is fractional distillation?
It is used to separate two or more liquids that have been mixed together
What is the method of simple distillation?
The solution is heated and a liquid evaporates producing vapour, the vapour passes through the condenser, where it cools and condenses, turning into the pure liquid into the beaker.
After all the liquid has been collected the solid solute is left behind.
What was JJ Thompson’s theory?
JJ Thompson proposed atoms were in a plum pudding structure.
He suggested that the atom was a positively charged sphere with negative stuck into it.
What was John Dalton’s theory
Dalton proposed that atoms were solid spheres.
He suggested that compounds/molecules could be broken down into separate spheres
Properties of an impure substance (Two)
- Mixture of two or more elements or compounds.
- They melt and boil over a range of temperatures
What activities lead to the increase of greenhouse gases? (Three)
- Carbon dioxide produced during combustion of fossil fuels in power stations and cars
- Deforestation causes less CO2 to be taken in by photosynthesis
- Methane is produced and released from landfill sites as waste decomposes
How is carbon monoxide formed?
Incomplete combustion of hydrocarbons
What is the formula for Alkenes
CnH2n
Properties of pure substances (Two)
- Substance containing just one element or one compound.
- Identified using its fixed points
Test for chlorine
Damp blue litmus paper turns white
What is the greenhouse effect? (Three)
- The sun emits short-wave electromagnetic radiation e.g. UV which warms the Earth
- The Earth loses heat by emitting long-wave radiation e.g. thermal radiation.
- Greenhouse gases in the atmosphere absorb some of this long-wave infrared and radiates in all directions (keeps the Earth the correct temperature).
What is the formula to find the Rf value?
Distance moves by substance ÷ Distance moved by solvent.
What is the method of fractional distillation?
The solution is heated to the temperature of the substance with the lowest boiling point.
The substance will rise and evaporate first, vapours go through a condenser where they cool and condense into a liquid into a beaker.
This will leave behind the other components in the mixture.
What is the process involving the mobile phase and stationary phase?
The mobile phase moves through the stationary phase, carrying the components of the mixture under investigation. Each component in the mixture will have a different attraction for the mobile and stationary phase.
What are the definitions of:
a). Alkalis
b). Neutral substances
- Alkalis are a specific group of bases that are soluble in water, they are soluble hydroxides. e.g. sodium hydroxide solution
- Neutral substances are substances that are neither acids nor bases. e.g. water
What is chromatography?
Used to separate and identify mixtures of amino acids
What is a formulation? (Two)
- A formulation is a mixture that has been designed to produce a useful product e.g. medical drugs, paint.
- Other formulations are: fuels, alloys, fertilisers, pesticides, cosmetics and some food products.
What is simple distillation?
It is used to spearate a mixture where the solid has dissolved and so a solution has formed
Colour change from alkane water + bromine water
Stays orange
Ethene
No. of carbons:
No of hydrogens:
Formula:
Structure:
- 2 carbons
- 4 hydrogens
- CnH2n
- C=C - H - H - H - H
What are alkenes? (Three)
- Family of hydrocarbons
- Each contains one carbon-carbon double covalent bond
- Double bond = unsaturated
Why do we do cracking? (Two)
- Smaller alkanes (C-C single bonds) are useful as fuels.
- The alkene (one C=C double bond) produced can be made into polymers and used as plastics
