Chemistry ✿ required practicals

describe a method to investigate how the temperature changes when different masses of ammonium nitrate are dissolved in water. [6]

• add 25cm³ water to a polystrene cup

• so no heat is lost

• place a lid on the cup and use a themometer to take start temeprature

• add 1 gram of ammonium nitrate and stir to dissolve. take the new temperature and record in table

• repeat using 2g, 3g, 4g and 5g, adding fresh water each time

• repeat steps to calculate mean.

why is cryolite used in electroloysis?

to lower aluminium oxide’s melting point

why are carbon rods used in electroloysis?

has delocalised electrons, making it a conductor

why are the carbon electrodes replaced frequently?

oxygen reacts with carbon so some carbon is lost

Plan a method to make pure, dry crystals of zinc chloride from zinc carbonate and a dilute acid. [6]

• pour acid into beaker and gently heat using water bath

• add zinc carbonate in excess

• filter excess using filter paper and funnel

• pour solution into evaportion dish

• heat using bunsen burner

• once crystals form, leave out to dry

anode

positive electrode

cathode

negative electrode