c6 rates exam questions Flashcards
on a graph that shows the rate of reaction with volume of gas produces on the y axis, and the time on the x axis. the line starts flattening near to the end. explain why the liens of best fit have become horizontal (2)
-the reaction has stopped
-because the reactants have been used up
a balance is used to weigh 10g of calcium carbonate lumps caused an error. the balance always read 0.2g before being used. what type of error was caused by the balance? (1)
systematic error
ethanoic acid ionises in water, the equation is:
CH3COOH <–> CH3COO- + H+
explain how the equation shows that ethanoic acid is a weak acid (2)
- ethanoic acid only partially ionises
- because the reaction is reversible
A student adds a solution of ethanoic acid to zinc carbonate in an open
flask on a balance.
Explain what happens to the mass of the flask and its contents during the
reaction. (3)
- mass of flask and contents decreases
- because carbon dioxide is produced
- and carbon dioxide escapes from the flask
Methanoic acid has pH of 2.91 mol/dm^3
Ethanoic acid has pH of 3.39 mol/dm^3
The student compares the rates of the reaction of zinc carbonate with:
* 0.01 mol/dm3 methanoic acid
* 0.01 mol/dm3 ethanoic acid.
The rate of the reaction with methanoic acid is greater than the rate of the
reaction with ethanoic acid.
Explain why.
You should refer to ions in your answer. (3)
- methanoic acid has a lower pH
- so it has a higher concentration of
hydrogen ions - therefore more collisions per unit time
Give the name of the ester produced when ethanoic acid reacts with ethanol (1)
ethyl ethanoate
A small cube has sides of 0.5cm. A larger cube of calcium carbonate has sides of 5 cm
Describe how the surface area to volume ratio of this larger cube differs the first cube (1)
decreases by a factor of 10
What two pieces of measuring apparatus could the student use to find the rate of production of hydrogen gas? (2)
- gas syringe
- timer/ stopwatch
