Which of the following statements about fuel cells is false?
Water is the only product
They will operate continuously
They produce electricity
They convert electricity into heat
Which of the following are advantages of fuel cells?
Direct energy transfer
Less pollutants
No recharge limit
Hydrogen is a gas
Hydrogen is explosive
Hydrogen is produced from fossil fuels, or electrolysis
The overall reaction in a hydrogen fuel cell involves the oxidation of hydrogen to produce water.
Simple chemical cells work because the metals used have different reactivities.
If a reaction should produce 50 g of product, but only produces 42 g, calculate the percentage yield (2 s.f.): %
What is the atom economy for this reaction, where hydrogen is the desired product (give your answer to 2 s.f.)? %
The pathway chosen for a product depends on factors such as (select all that apply):
percentage yield
atom economy
rate of reaction
equilibrium position
usefulness of by-products
ability to transport products
When completing a titration, you will have multiple readings which you need to calculate an average reading for. It is important that the titres you include in your calculation are .
Which of the following is not a worry of nanoparticles?
people are concerned the small size of nanoparticles makes it possible to breathe them in, or to pass into cells
inside the body, they might catalyse reactions that are harmful producing toxic substances
modern nanoparticulate materials have not been used for long, so it is difficult for scientists to determine their risks
individual particles (nanoparticulate) of titanium dioxide have no colour and cannot be seen when it is spread on skin
Compared to other metals, most transition metals have the general properties of:
higher melting points
lower densities
greater strength
lower hardness
form coloured compounds
have catalytic activity
The group 1 elements react quickly with oxygen in the air at room temperature. Most transition elements react slowly, or not at all, with oxygen at room temperature.