the single variable that is changed in an investigation

the single variable that is measured or observed in an investigation

all variables, other than the independent and dependent variables, that are kept the same in an investigation

Heating curves: practical

Chemistry

The particle model

State changes: fundamentals

State changes: evaporation and sublimation

Predicting states of matter and limitations of the particle model

Pure substance

Heating and cooling curves

In the Separating Substances unit, pupils will build on their knowledge of states of matter to learn about different techniques for separating mixtures.

In the Solid, Liquid and Gas States and Changes of State unit, pupils learned about the properties of different states of matter and how particles move during changes of state.

This unit covers the particle model, states of matter, and changes between them, distinguishing physical from chemical changes. It explains the concept of purity in scientific terms, using melting point data to identify pure and impure substances, and explores the limitations of the particle model.

States of matter

Physical activity and equipment requiring safe use

it shows the temperature change every 30 seconds

it shows the temperature change between any two times

The table shows data from a heating curve experiment. What is the main reason why it is helpful to plot a graph of these results?

variable that you change or select values for

variable that you measure or observe to get your results

variable that must remain the same throughout an investigation

value that does not fit the pattern of the results

average calculated by adding all values, dividing by number of results

Match the key terms to their definitions.

calculate a mean average for each measurement

cross out any anomalous results and don't use them

cross out the biggest value from each set of repeat measurements

repeat the experiment to check measurements

What can you do to improve the reliability of a set of results?

the names of the pupil(s) you are working with

The table shows data from a heating curve experiment. What would be useful other information to record for each measurement?

this is a cooling curve for a pure substance

this is a heating curve for a pure substance

The image shows a results table from either a heating or a cooling curve experiment, and from either a pure substance or a mixture. Which of the following statements is true?

Considering the data in the table at the start of the experiment, which graph would be the most likely to represent the results for the whole experiment?

work out which safety precautions are needed

if needed, prepare a table to record results

Which of these are **essential** things you need to do when planning an experiment?

collect all the equipment on the equipment list

set up all the equipment as shown, with the Bunsen not yet heating the water

record the initial temperature of the substance

start the timer and start heating with the Bunsen at the same moment

record the temperature every 30 seconds until the water is boiling

note times and temperature at which the solid substance starts to melt

leave the equipment to cool before dismantling it and tidying away

Put the following steps in order to describe a method for collecting data to plot a heating curve of the solid substance shown in the boiling tube. Begin with 'collect all the equipment'.

to spread out the heat over the base of the beaker

to make sure the Bunsen burner cannot touch the tripod

to make the platform of the tripod a square shape

to prevent the water bath from overheating

to make the beaker more stable and less likely to fall

What is a gauze used for? On this diagram, it is represented by the wavy line between the tripod and the beaker.

A table for results should include columns to record independent and dependent variables and and other necessary information. The dependent variable is usually recorded in the {{}} column.

placing the equipment in the middle of the bench

Which safety precautions are needed for a heating curve experiment, in which a solid is melted in a water bath, with its temperature measured over time?

When transferring information from a results table to a graph, which variable should be plotted along the x-axis?

Starter Quiz

Which of these are essential things you need to do when planning an experiment?