PAG

Question 1

what do you need to know to make a standard solution

Answer 1

• know the concentration and volume of the solution you need to make
• work the amount in mole of solute needed
• convert this amount of solute into a mass in g, so that you know how much to weigh out

Question 2

how do you make a standard solution

Answer 2

1. weigh out the solute
2. dissolve the solute in solvent in a beaker, transfer the solution to the flask and rinse the beaker repeatedly using more solvents add the rinsings to the flask
3. add solvent to the flask but do not fill it all the way to the graduation flask
4. carefully add the slvent drop by drop to the line on the flask until the bottom of the meniscus sits on the graduation mark on the flask, if the solution goes over the meniscus line you need to throw it away and start again
5. mix the solution thoroughly by inverting the flask several times

Question 3

How the book says to carry out a titration

Answer 3

1. using a pipette, add a measure volume of one solution to a conical flask, add a suitable indicator
2. place the other solution in a burette
3. add the solution in the burette to the solution in the conical flask until the reaction has just been completed, this is called the end point of the titrations, measure the volume of the solution added from the burette
4. the volume of one solution that exactly reacts with the volume of the other solution

Question 4

direction measurement of enthalpy of a reaction

Answer 4

• add a measured mass of the first liquid reactant, take the temperature every minute until it is stable this usually takes 4 minutes
• at 5 minutes add the second reactant, do not take or record the temperature for a 5th minute
• monitor the temperature of the reaction mixture every minute for a further 5 minutes
• plot a graph to infer the maximum temperature change generated by the reaction

Question 5

direct measurement on enthalpy of combustion

Answer 5

• when a fuel is combusted the heat energy can be used to increase the temperature of a known mass of wate
• measure the starting mass of the fuel
• add a known mass of water to a copper calorimeter
• mount the copper calorimeter over the fuel and take the starting temperature of the water
• take the mass of the unused fuel and calculate the mass of the fuel burnt

Question 6

what order do you test unknown substances in

Answer 6

1. carbonate test
2. sulfate test
3. halide test