Y10 Spring Term Chemistry Round Up Flashcards
What is an exothermic reaction?
A reaction where more energy comes out than in. In an exothermic reaction the reactants have more energy than the products
What’s an endothermic reaction?
A reaction where more energy comes in than out. In a endothermic reaction the products have more energy than the reactants
Give an example of an exothermic reaction
Combustion, oxidation, neutralisation etc.
Give an example of a endothermic reaction
Thermal decomposition
What’s an example of an everyday use of an exothermic reaction and how does it do this?
Self-heating cans, hand warmers etc. They give out heat energy to the surroundings
What’s a example of an everyday use of a endothermic reaction and how does it do this?
Cool packs for sports injuries. Chemicals take in heat energy and cool the surroundings
What’s the reaction profile for an exothermic reaction?
Products are at a lower energy level than reactants
What’s the reaction profile for a endothermic reaction?
Products are at a higher energy level than reactants
What is activation energy?
The energy needed to start a reaction
What does the acronym BINMIX stand for?
(Bond) Breaking
Is
eNdothermic
(Bond) Making
Is
eXothermic
How does bond energy work in exothermic reactions?
More energy comes out making bonds
How does bond energy work in endothermic reactions?
More energy comes in breaking bonds
What is a pure substance?
A single element/compound that isn’t mixed with any other substance
What is formulation?
A mixture that has been designed as a useful product
What is chromatography?
A technique that can be used to separate mixtures and identify the substances
How do you test for carbon dioxide gas?
It turns limewater cloudy/milky
How do you test for hydrogen gas?
Bringing a lit splint into the presence of hydrogen gas causes it to make a squeaky pop sound
How do you test for oxygen gas?
You hold a glowing splint at the open end of a test tube If the glowing splint relights then the test tube contains oxygen
How do you test for chlorine gas?
To test for chlorine, you use damp litmus paper. When chlorine gas is present the gas bleaches the paper white
What was Earth’s early atmosphere like?
It is unclear what Earth’s early atmosphere was like. However most scientists agree that Earth’s atmosphere most likely contained carbon dioxide, nitrogen, methane and ammonia
What caused the makeup of Earth’s early atmosphere?
Heavy volcanic activity
How were oceans formed?
From condensed water. Carbon dioxide dissolved in the oceans, carbonates precipitated (turned into solid bits) to form sediments
How were plants/algae formed?
Took in carbon dioxide and released oxygen in photosynthesis.
How were sedimentary rocks/fossil fuels formed?
Decreased carbon dioxide levels
What are the greenhouse gases?
- Carbon dioxide
- Methane
- Water Vapour
What are the stages of the Greenhouse Effect?
1) Some short-wavelength radiation
(ultraviolet) passes straight through the atmosphere and is reflected, without heating it up. This radiation doesn’t interact with the gases in the atmosphere
2) Most radiation is absorbed by Earth’s surface and warms it
3) The Earth’s surface re-emits energy as longer wavelength infrared radiation that interacts with the gases in the atmosphere
4) Some of the infrared radiation is absorbed by greenhouse gas molecules. This warms up the Earth’s surface and the atmosphere
What causes climate change?
Human activities increase the levels of carbon dioxide and methane
What human activities contribute to climate change?
CO2:
- Burning fossil fuels
- Deforestation
Methane:
- Cow farming (and rice paddies)
- Landfill sites
What are the effects of climate change?
- Rising sea levels
- Droughts
- Extreme weather events
- Changes in wildlife distribution
Why do some people deny that humans contribute to climate change?
- Difficult to model
- Models are simplified
- The media can be biased
- Must check that the evidence is peer reviewed
What is a “carbon footprint”?
The total amount of CO2 and other greenhouse gases emitted over the full life cycle of a product, service or event
What are some solutions to combat climate change?
- Reduce carbon footprint
- Use less fossil fuels
- Carbon capture and storage
- Eat less meat
- Send less food waste to landfill
What are the gases released in the combustion of fossil fuels and how do they effect the planet?
Carbon dioxide:
- Released when all fossil fuels burn
- Causes global warming
Water Vapour:
- Released when all fossil fuels burn
- Has no harmful consequences
Carbon monoxide:
- Released by incomplete combustion of fossil fuels (not enough O2)
- Causes a poisonous gas deadly to humans
Solid particulates:
- Released when solid fuels burn incompletely
- Causes global dimming and asthma
Sulphur dioxide:
- Released when coal burns
- Causes acid rain and respiratory problems
Nitrous oxides:
- Released when nitrogen in the air reacts with oxygen
- Causes acid rain and respiratory problems
