Paper 3 Recap

Question 1

What is the equation when working out the gradient in the Arrhenius equation?

Answer 1

m= - Ea/R

Question 2

Rearrange m= - Ea/R to make EA the subject

Answer 2

Ea = R x (-gradient)

Question 3

What is the equation to plot a graph? *y

Answer 3

y = mx + c

Question 4

What is new Arrhenius equation that allows us to plot a graph using y= mx +c

Answer 4

Ln (k) = -Ea/R x 1/T + Ln(A)
y = m x x + c

Question 5

What reactants test for Ammonium?
What is produced? 2
What is used to test for the positive test? And what is the positive test itself?

Answer 5

• NaOH
• Precipitate in test tube and gas of NH3
• Fumes turn Red litmus’s to Blue litmus’s paper

Question 6

What is the eq for the reaction for the ammonium test?

How does the positive test occur? And give the eq

Answer 6

-NH4+ + OH- ➡️ NH3 + H2O

-OH- that is formed when NH3 reacts with the H2O on the litmus changes the paper from Red ➡️ Blue
NH3 + H2O ➡️ OH- + NH4

Question 7

What chemical can be used to test CO3 2-?
What is the positive test? 2 What chemical apparatus can be used to ensure it’s a positive test!

Answer 7

-Dilute HCl

-effervescence, CO2
-bubbled through lime water

Question 8

What is the chemicals used to test for sulphates SO4 2-? *2 chemicals

What is the positive test and what chemical does it produce?

Answer 8

1. HCl
2. BaCl2

BaSO4 white precipitate