Brainlag PlusDraw your own tangents on gas and mass curves, find the initial rate, compare rates at two times and give a rate in mol/s.
Drawing a tangent yourself
A tangent touches the curve at one point and has the same steepness as the curve there.
On a paper you draw it yourself, so the mark scheme accepts a range of answers.
- Mark the point on the curve at the time you are given
- Lay a ruler so it touches the curve only at that point, not cutting through it
- Draw a long straight line: the longer it is, the more accurate the gradient
- Pick two points on the line far apart, where they cross gridlines if you can
- rate = change in volume ÷ change in time, using those two points
- Tangent at 25 s through (0, 13.2) and (50, 50.0)
- gradient = (50.0 − 13.2) ÷ (50 − 0) = 36.8 ÷ 50
- rate at 25 s = 0.74 cm³/s
The rest of this lesson and its 7 practice questions are in Plus.
Screen 1 of 3, free to read.
- 7 exam-style questions, marked as you go, each with a worked solution
- Anything you get wrong is saved to your flashcards