Unit 2 Flashcards
How do you get from g/dm^-3 to mol/dm^-3?
Mass = moles x Mr
Therefore, moles = Mass/Mr
How do you get from mol/dm^-3 to g/dm^-3?
Mass = moles x Mr
What is the equation you would use to find an unknown volume or concentration, assuming you were given 3 already and had to find the 4th?
MV (substance A) moles of A
_____________ = __________
MV (substance B) moles of B
M = Molarity V = Volume
What is the equation for percentage uncertainty?
Percentage = (uncertainty/reading) x 100
What are two indicators used in Titrations?
Methyl Orange and Phenolphthalein
When adding acid to alkali, what colour changes do both indicators endure?
Methyl Orange: yellow - red
Phenolphthalein: red - colourless
Why is Universal Indicator not used for Titrations?
The colour change is too gradual.
What is ozone?
O3
Where is the ozone layer?
In the stratosphere.
Write the equation(s) to show how ozone is destroyed by chlorine free radicals.
Cl@ + O3 —> O2 + ClO@
ClO@ + O3 —> 2O2 + Cl@
How do chlorine free radicals form?
CFCs are broken down by ultraviolet (UV) radiation to form chlorine free radicals.
Which bond in CFCs are broken when chlorine free radicals are formed?
Carbon-chlorine bonds.
Why are chlorine free radicals an example of a catalyst during the reaction in which they break down ozone?
The free radicals stay in the same form throughout the reaction - they are not used up and do not change.
What other free radical can damage the ozone layer?
Nitric oxide.
Where do nitric oxide free radicals come from?
Nitrogen dioxide.
How does nitrogen dioxide enter the atmosphere?
Through:
- Car engines
- Aircraft engines
- Thunderstorms
How does ozone form and what is the equation for the reaction of it’s formation?
UV radiation from the sun hits oxygen molecules.
O2 + hv (UV) —> O@ + O@
O@ + O2 —> O3
What reasons do humans have for wanting to keep the ozone layer fully intact?
It prevents harmful, (high energy), UV radiation from reaching Earth. This energy can damage DNA in cells and can cause skin cancer.
What reasons do humans have for wanting to keep the ozone layer fully intact?
It prevents harmful, (high energy), UV radiation from reaching Earth. This energy can damage DNA in cells and can cause skin cancer.
What is the tropopause?
The boundary in the Earth’s atmosphere between the troposphere and the stratosphere.
What happens (and what is the reaction) when UV radiation is absorbed by ozone which enables ozone to protect oxygen in the troposphere from UV light?
When ozone absorbs UV radiation in the stratosphere, oxygen is produced.
O3 + hv (UV) —> O2 + O@
O3 + O@ —> 2O2
Ozone and oxygen both react with UV radiation. If there was no human influence, the thickness of the ozone layer would stay the same. Why?
The rate of production and destruction of ozone in the stratosphere is the same. The ozone layer is being constantly destroyed and replaced. It can be represented by an equilibrium reaction:
O2 + O@ —>
What happens when hydrogen halides react with Ammonia and what is the reaction for it?
White fumes form.
NH3 + HX —> NH4X
X = any halide
How soluble are hydrogen halides in water?
Very soluble. They form strong acids.
What does hydrogen chloride form in water?
Hydrochloric acid
What does hydrogen bromide form in water?
Hydrobromic acid
What does hydrogen iodide form in water?
Hydroiodic acid
Does the reducing power of halide ions increase or decrease down the group and why?
The reducing power of the ions increases.
Reducing means to gain electrons, so the ability of ions to give electrons to other atoms improves down the group because…
- the atomic radius increases
- there are more shells of electrons, increasing shielding.
Write the equation for the reaction between Potassium Fluoride and sulfuric acid.
KF + H2SO4 —> KHSO4 + HF
Why does the product of the reaction between Potassium fluoride and sulfuric acid means that there are no further reactions?
The product is HF, which is not a strong enough reducing agent to reduce sulfuric acid.
Write the equation for the reaction between Potassium Chloride and sulfuric acid.
KF + H2SO4 —> KHSO4 + HF
Write the equation for the reaction between Potassium Bromide and sulfuric acid.
KBr + H2SO4 —> KHSO4 + HBr
2HBr + H2SO4 —> Br2 + SO2 + 2H2O
Write the equation for the reaction between Potassium Iodide and sulfuric acid.
KI + H2SO4 —> KHSO4 + HI
2HI + H2SO4 —> I2 + SO2 + 2H2O
What is produced when haloalkanes react with Ammonia?
Amines
What is the functional group of amines?
A nitrogen atom with a lone pair of electrons.
Write the equation for the reaction between 1-iodobutane and ammonia.
C4H9I + NH3 —> C4H9NH2 + HI
