Acid-alkali Titration

Question 1

A few drops of methyl orange are added to a beaker of alkali. What will you observe when adding acid to beaker?

Answer 1

Methyl orange will change from yellow to orange to then red

Acid - red
Alkali - yellow
Neutral- orange

Question 2

A few drops of phenolphthalein are added to a breaker of acid. What will you observe when adding alkali?

Answer 2

Colour change from colourless to pink
Acid - colourless
Neutral - colourless
Alkali - pink

Question 3

How is water formed in a reaction between an acid and alkali?

Answer 3

H+ ions from acid react with OH- ions from alkali

Question 4

List the apparatus required to carry out a titration

Answer 4

Burette
Conical flask 
Clamp stand 
Pipette 
Small funnel
White tile

Question 5

Describe how to set up a titration and complete a titration

Answer 5

Use a pipette to add a known volume of alkali to a conical flask
Add a few drops of indicator
Fill the burette with acid using a funnel
Open the tap of burette slowly add the solution (drop wise) to the conical flask, swirling to mix
Close the Tap when the end point is reached
Record the volume
Repeat without indicator

Question 6

What safety precautions should be taken when carrying out a titration?

Answer 6

Clear up spillages or broken glassware
Wear safety goggles and gloves
Fill burette below eye level using a funnel
Be aware of the harmful effects of the chemicals use e,g irritant, corrosive

Question 7

Why is an indicator used in titration?

Answer 7

To show when the end point has been reached

Question 8

Why is a white tile use in a titration?

Answer 8

The white tile is placed under the reaction mixture to make the colour change easier to see

Question 9

What is the purpose of repeating a titration?

Answer 9

To obtain concordant results, allow a mean titre to be calculated, and reduce the effect of random error.

Question 10

Why is a trial titre carried out?

Answer 10

To find the rough volume require to reach end point

To quickly check that the end point can be reached with the concentrations and volumes being used

Question 11

What are concordant results

Answer 11

Titres which are within 0.20cm3 (or 0.10cm3) of each other

Question 12

How do you calculate mean titre?

Answer 12

Add the 2 concordant results and divide by 2

Question 13

Why is volumetric pipette use to measure the volume of acid or alkali added to the conical flask?

Answer 13

Greater accuracy than a measuring cylinder