Density and properties of matterIB MYP Chemistry: Mind map

Exam questions on Density and properties of matter

1. A jeweller in Jaipur wants to check whether a small shiny bar is pure gold or a cheaper metal that looks similar. The bar is a cuboid measuring 2.0 cm by 1.5 cm by 2.5 cm. She finds its mass is 96.5 g.
   Pure gold has a density of 19.3 g/cm³. Decide whether the bar is pure gold and justify your answer.2 marks
2. A student in São Paulo wants to find the density of an irregular piece of rock. She finds that the rock has a mass of 84 g. She half-fills a measuring cylinder with water and reads 50 cm³. She lowers the rock into the water on a thread and the water level rises to 82 cm³.
   Calculate the density of the rock in g/cm³. Give your answer to 2 significant figures.2 marks
3. A student in Cape Town wants to find out how adding salt changes the density of water. She dissolves different masses of salt in 100 cm³ of water to make four solutions, all at the same temperature. For each solution she measures 50 cm³ in a measuring cylinder and finds the mass of the 50 cm³ sample using a balance.
   Identify the independent variable, the dependent variable and one control variable.3 marks