IB DP Chemistry: HL復習筆記6.1.2 Rate of Reaction

Category: IB課程, 教材筆記, 福利干貨 Date: 2022年7月27日下午4:56

Rate of Reaction

Reaction rate

Some reactions take place instantly, but most are much slower and it is possible to measure how long these reactions take to reach a certain stage
As a chemical reaction proceeds, the concentration of the reactants decreases and the concentration of the products increases
The?rate of a reaction?is the speed at which a chemical reaction takes place and has units?mol dm^-3?s^-1
The rate of a reaction can be calculated by:

6.1.2-Rate-of-reaction-formula

Graphically we can represent the rate of reaction as:

6.1.2-Rate-of-reaction-graphs

Rate of reaction graphs

Worked Example

Iodine and methanoic acid react in aqueous solution.

I₂?(aq) + HCOOH (aq) → 2I^??(aq) + 2H⁺?(aq) + CO₂?(g)

The rate of reaction can be found by measuring the volume of carbon dioxide produced per unit time and plotting a graph as shown 6.1.2-Rate-of-reaction-Worked-Example-Question Calculate the rate of reaction at 20 seconds

Answer:

- Draw a tangent to the curve at 20 seconds:

6.1.2-Rate-of-reaction-Worked-Example-Answer

- Complete the triangle and read off the values of x and y
- Determine the gradient of the line using ?y / ?x
- Rate of reaction = 24?÷ 40 =?0.60 cm^3?s^-1

Exam Tip

When drawing the tangent to a curve make the triangle large and try to intersect with gridlines if you can. This minimises errors of precision and reduces the chance you will accidently misread the graph values

轉載自savemyexams