Formative Lab Exercise 2 – CEM131
Molar Mass and Molar Ratios: The Formula of a Hydrate
Mass and mole relationships are a crucial aspect of chemistry. Chemical equations are a means of communicating what is happening in a reaction. The coefficients of a balanced chemical equation represent the moles of reactants and products involved in a reaction. In this activity, you will heat a hydrated compound of copper (II) sulfate. This heating will drive off the water of hydration. You will then use the data that you will collect to determine the mole ratios of water to copper (II) sulfate to balance the following equation.
CuSO4 . ? H2O(s) + heat –> CuSO4 (s) + ? H2O(g)
Determine the mass of the three beakers to the nearest 0.01 g (mtube). Record these data in your data table.
Weigh a sample of 0.45-0.55 g of hydrated copper (II) sulfate into each of the beakers
Determine the mass of each beaker plus hydrated copper (II) sulfate to the nearest 0.01 g (mhydrated). Record these data in your data table.
Lay the test tubes on a heat block and gently heat the test tubes. Begin at the closed end, and heat slowly.
When heated, the blue hydrated copper (II) sulfate is transformed to white, anhydrous copper (II) sulfate. When the entire sample has turned white.
Turn off the heat block and allow the beakers to cool to room temperature.
Determine the mass of each beaker plus anhydrous copper (II) sulfate to the nearest 0.01 g (mdried).
Repeat the heating and cooling steps until a constant weight is obtained.
Date Images for the Experiment
Empty Beaker (mtube) Beaker with Hydrated Salt (mhydrated) Beaker with Dehydrated Salt (mdried)
Trial 1 Trial 1 Trial 1
Trial 2 Trial 2 Trial 2
Trial 3 Trial 3 Trial 3