18.3 rate-concentration graphs and initial rates Flashcards Preview

Fckn Chemistry Module 5 > 18.3 rate-concentration graphs and initial rates > Flashcards

Flashcards in 18.3 rate-concentration graphs and initial rates Deck (13):
1

What does a 0 order rate-concentration graph look like?

A horizontal straight line, with a 0 gradient and the u-intercept =k

2

What does a first order rate-concentration graph look like?

A straight line through the origin, gradient = k, positive gradient

3

What does a second order rate-concentration graph look like?

An upward curve with increasing gradient, gradient = k an d the graph is plotted rate-con^2

4

How is the initial rate of a reaction calculated?

It is the instantaneous rate at the start of a reaction when time=0, it is found by measuring gradient at t=0 on a concentration- time graph

5

What is a clock reaction?

A convenient way of obtaining initial rate with a single measurement

6

How do you carry out a , iodine clock reaction?

Several experiments are carried out with different concentrations of one reactant with all other reactant concentrations staying constant

7

How can the colour change of an iodine clock reaction be delayed?

By adding a small amount of another chemical such as Na2S2O3, which removes iodine as it forms

8

What will the colour change be in an iodine clock reaction?

Colourless to blue/black if starch is present or organge/brown if not

9

What measurements do you take in an iodine clock reaction?

You measure the time taken for the colour change to take place

10

In an iodine clock reaction, what is initial rate proportional to?

1/t (provided there was no significant change in reaction between t=0 and colour change)

11

In an iodine clock reaction, what graph is plotted?

1/t against concentration

12

How can order be determined from an iodine clock reaction?

Carry out lots of reactions changing the concentrations of other reactants

13

How accurate is a rate-concentration graph?

In a shorter period of time, the less the rate changes the more accurate the measurement but they are reasonably accurate providing less than 15% of the reaction has taken place