PHYSICAL topic 2 -amount of substances

Question 1

State and explain the effect, if any, that rinsing the burette with deionised water before filling it with
NaOH solution will have on the value of the titre {2}

Answer 1

. titre value increase
. cos NaOH solution become more dilute

Question 2

what are units of pressure in PV=nRT {1}

Answer 2

Pa

Question 3

what are units of volume in PV=nRT {1}

Answer 3

m^3

Question 4

Compound contains 40.0% carbon, 6.7% hydrogen & 53.3% oxygen by
mass.
what is molecular formula

Answer 4

. 40/12= 3.3
6.7/1= 6.7
53.3/16= 3.3

Question 5

percentage atom economy equation

Answer 5

Mr of desired product(times the moles)/ sum of reactant Mr(times the moles) x100

Question 6

percentage yield equation

Answer 6

percntg yield =
actual mass/theoretical mass

Question 7

what is importance of atom economy {1}

Answer 7

.minimise as much by product mass as possible

Question 7

what is importance of percentage yield {1}

Answer 7

.efficient conversion of reactants to products

Question 8

percentage uncertainty equation

Answer 8

percentage uncertainty = error/value

Question 9

Suggest why the electronegativity of the elements increases from lithium to fluorine.

Answer 9

. More protons, bigger nuclear charge
. atoms get smaller