PPQ Flashcards
Give two properties of transition metals
Form coloured compounds
Variable oxidation states
A student investigated the effect of
changing the concentration of hydrochloric acid on the maximum temperature reached by the reaction mixture. Plan a method to investigate how changing the concentration of hydrochloric acid affects the highest temperature reached by the reaction mixture.
● measure volume of HCl with measuring cylinder and pour into polystyrene cup
● measure initial temperature of HCl with a thermometer
● add a known mass of Mg (measured with balance) and stir
● measure highest temperature reached
● repeat with different concentration of HCl
acid
● repeat whole investigation and find mean for each concentration
● use same starting temperature and same volume of HCl each time
Give an advantage and a disadvantage of using hydrogen fuel cells to power an electric car.
Advantage:
- Clean energy source, emitting only water as a byproduct.
- Higher energy density compared to traditional batteries, allowing for
longer driving ranges.
Disadvantage:
- Limited hydrogen infrastructure, making refuelling stations scarce.
- Production of hydrogen often relies on energy-intensive processes,
reducing overall efficiency.
Draw a diagram of a hydrogen fuel cell.
https://cdn.savemyexams.com/cdn-cgi/image/w=1920,f=auto/uploads/2020/02/Hydrogen-oxygen-fuel-cell.png
Which two substances have intermolecular forces between particles out of:
Diamond
Magnesium
Poly(ethene)
Sodium chloride
Water
water and poly(ethene)
Compare the structure and bonding of the three compounds:
* carbon dioxide
* magnesium oxide
* silicon dioxide
- bothCO2 and SiO2 are made up of atoms but MgO is made up of ions
- both SiO2 and MgO are giant structures but CO2 is small molecules with weak IMF
- all 3 compounds have strong bonds
- Both CO2 and SiO2 are formed from two
non-metals so the bonds are covalent which means electron pairs are shared between atoms; but MgO is formed from a metal and a non-metal so bonds are ionic
which means 2 electrons are transferred from Mg to O - bonds in SiO2 are single bonds where each Si forms 4 bonds and each O forms 2 bonds; but in CO2 the bonds are double bonds where C forms 2 double bonds and O forms 1 double bond
A student is given three metals, X, Y and Z to identify. The metals are Mg, Fe and Cu. Plan an investigation to identify the 3 metals by comparing their reactions with
dilute HCl
- add the metals to HCl and measure
for Cu: - no reaction shown by no temperature change
for Mg and Fe: - Mg increases in temperature more than Fe
Control variables - same concentration / volume of hydrochloric acid
- same mass / moles of metal
- same particle size of metal
The student purified separated silver iodide. By rinsing the silver iodide with distilled water then warming it.
Suggest one impurity that was removed by rinsing with water and why the student warmed the silver iodide
a) sodium nitrate (solution) or silver nitrate (solution) or sodium iodide (solution)
b) to evaporate water
Give one reason why reactions with a high atom economy are used in industry.
- for sustainable development
- for economic reasons
- to produce a highqer percentage of useful product
Why is it not correct to say that the boiling point of a single bromine molecule
is 59 °C?
boiling point is a bulk property
Figure 6 shows an anomalous point when 0.60 g of citric acid was added.
This was caused by the student making an error.
The student correctly:
* measured the mass of the citric acid
* read the thermometer
* plotted the point.
Suggest one reason for the anomalous point.
they didn’t stir enough
give 2 reasons why burettes are used for titrations
- can add acid in small increments
- can measure variable volumes
- more accurate than a measuring cylinder
