paper 1 practise

Question 1

how to calculate no. of atoms/electrons removed

Answer 1

mass/mr x 6.02x10^23

Question 2

what anomalies are there in transition elements?

Answer 2

Cr/Cu as they both have 4s^1

Question 3

Explain why the boiling point of PH3 is lower than the boiling point of NH3 (both in group 5)

Answer 3

• NH3 has hydrogen bonding (FON)

- H bonding is a much stronger imf

Question 4

explain why the boiling point of PH3 is lower than the boiling point of AsH3 (both in group 5)

Answer 4

• As has more electrons than P

- in AsH3 stronger induced dipole-dipole interactions

Question 5

what is the systematic name for KClO4?

Answer 5

potassium chlorate (VII)

Question 6

^G diagram what parts of the graph indicate what?

Answer 6

P/y-axis=enthalpy change/delta H
gradient= - delta S
link to y=mx+c
where Q/y intercept at (x-axis temperature) crosses is where the reaction becomes feasible

Question 7

suggest apparatus that would allow gas volume to be collected

Answer 7

using a 1dm^3 gas syringe

Question 8

suggest a different experimental method that would allow the rate of this reaction to be followed over time

Answer 8

measure mass loss

Question 9

how to calculate rate constant

Answer 9

rate/[a][b]

Question 10

general idea of equilibrium and temperature

Answer 10

endo direction=increase temperature to get it in the endo direction
exo direction=decrease temperature to get it in the exo direction

Question 11

why may operational conditions used by the chemical industry be different?

Answer 11

low temp/pressure=slow rate

high temperature=large amount of energy/fuel needed and used

Question 12

general rules in Kc units

Answer 12

more top than bottom=mol+ dm-

more bottom than top=dm first and + then mol -

Question 13

when the student prepares the buffer solution, the volume of solution increases slightly, what is the effect on the pH?

Answer 13

stays the same as the ratio/proportion of [HA]/[A-] is the same

Question 14

define average bond enthalpy

Answer 14

breaking one mol of bonds in gaseous molecules

Question 15

how to calculate Ea from lnk 1/T graph

Answer 15

-gradient x 8.314 (R)

Question 16

how to calculate pre-exponential factor, A

Answer 16

A=e^lnA

Question 17

chemist increases the pressure of the equilibrium mixture at the same temperature state/explain in terms of Kp how you’d expect the equilibrium position to change

Answer 17

• eqm shifts to RHS
• ratio in Kp decreases
• ratio then increases to restore Kp

Question 18

describe and explain how the student should determine the end point of this titration accurately (when S2O3)

Answer 18

add starch near end point as it goes from blue to colourless

Question 19

electron configuration rules transition elements

Answer 19

put 3d first then if able to remain partially filled add 4s

Question 20

link between equilibria and electrode potentials

Answer 20

more negative E=shifts to LHS

more positive E=shifts to RHS

Question 21

define weighted mean mass

Answer 21

the average mass taking into account the relative abundancies of the isotopes

Question 22

what gives the numerical value of the avogadro constant? (1 marker on multiple choice)

Answer 22

number of electrons lost by 20.05g of calcium when it reacts with oxygen

Question 23

20cm3 of 0.10 moldm-3 HCl is added to 10cm3 of 0.10 moldm-3 NaOH what is the pH of the resulting mixture (how would you calculate this?)

Answer 23

1. excess mol HCl =0.1/0.1=1 mol
2. excess mol/final volume=1/30=0.03
3. square root 0.03 to get 0.173
4. then do pH calculation -log to get 0.73 and x by 2 to get a pH of 1.48

Question 24

what is the key part in calculating the no. of ions via avogadros constant

Answer 24

to x moles by how many ions there are e.g.MgBr2=3 ions therefore you times mol by 3

Question 25

give an example of a lattice enthalpy equation

Answer 25

2Br-(g) + Mg2+(g)—>MgBr2(s)

Question 26

why would a large excess of methanol be used in an order of reaction experiment?

Answer 26

to keep it effectively constant