Using the equation of a straight line

By 2012-11-01T00:00:00

Figure 1 - Key parameters of a straight line graph

Gradients in chemical calculations

The equation of a straight line is usually taught in the form:

y= mx + c 

which succinctly expresses the fact that if we plot y against x and the variables obey a relationship of this form we will obtain a straight line graph with gradient or slope m and intercept (where the line crosses the y -axis) c (fig 1). 

In chemistry the letter c  is often used to represent concentration so this is potentially confusing. The letter used to represent the intercept is quite arbitrary, so it is perfectly acceptable to use - as we will for the remainder of this article - the equation in the form y = m x + b as b is a less commonly used symbol. Indeed, this is the form of the equation routinely used in some other countries and several variations are used around the world.1

Paul Yates discusses tips for teaching gradient in chemical calculations

Thanks for using Education in Chemistry. You can view one Education in Chemistry article per month as a visitor. 

A photograph of a teacher standing in a white lab coat, speaking with a class of children in a laboratory, is superimposed on a colourful background. Text reads "Teach Chemistry means support for classroom and staff room".

Register for Teach Chemistry for free, unlimited access

Registration is open to all teachers and technicians at secondary schools, colleges and teacher training institutions in the UK and Ireland.

Get all this, plus much more:

  • unlimited access to resources, core practical videos and Education in Chemistry articles
  • teacher well-being toolkit, personal development resources and online assessments
  • applications for funding to support your lessons

Set up your Teach Chemistry account

Already a Teach Chemistry member? Sign in now.

Not eligible for Teach Chemistry? Sign up for a personal account instead, or you can also access all our resources with Royal Society of Chemistry membership.