moles and solution

Question 1

how to calculate concentration

Answer 1

amount of solute (moles or grams)/ volume of solvent

Question 2

how to convert mol dm-3 to g dm-3

Answer 2

mol dm-3 =g dm-3/Mr

Question 3

what is an acid base titration

Answer 3

when you react a solution of an acid with a solution of an alkali.

Question 4

what is a standard solution

Answer 4

a solution of known concentration.

Question 5

how to make a standard solution

Answer 5

by dissolving an accurately weighed mass of solid in a known volume of solvent using a volumetric flask.

Question 6

what is the method to create a standard solution

Answer 6

-weigh desired mass of solid using a 2 or more decimal place balance
-dissolve in distilled water
-transfer to 250 volumetric flask using funnel
-Rinse the beaker and glass rod twice with small quantities of water, adding all
washings to the flask through the funnel
-make up to the mark with more distilled water up to about cm of the mark so that the bottom of the meniscus is on the mark
-use a dropping pipette when filling to the mark for more accuracy
-add the stopper and invert several times to mix

Question 7

what is the titre

Answer 7

the difference between the final and initial burette readings

Question 8

what is a concordant result

Answer 8

-two titre reading within 0.10 cm3
-these are used to calculate an
average titre value

Question 9

how to carry out titration

Answer 9

-Use a pipette to measure a volume of one solution to a conical flask
-Add a suitable indicator
-Add the solution in the burette to the solution in the conical flask until the
reaction has just be completed (change in colour of indicator).

Question 10

what is the end point with methyl orange for different pH

Answer 10

acid–> deep orange
neutral–> pale orange
-alkali–> yellow orange

Question 11

what is the end point with for Phenolphthalein different pH

Answer 11

acid–> colourless
neutral –> colourless
alkali–> pink