OCR A level Chemistry Data Sheet

What is in the OCR A level Chemistry Data Sheet?

The data sheet comprises 4 pages:

• Page 1 - Cover page

• Page 2 - General information and characteristic infrared absorptions in organic molecules

• Page 3 - ¹³C NMR chemical shifts relative to TMS and 1H NMR chemical shifts relative to TMS
  Page 4 - The Periodic Table of the Elements

Cover Page

• There is no specific chemistry data on the cover page.

• You should always be provided with the most up-to-date version of the datasheet. The current version is copyrighted by OCR in 2020 and this can be seen in the bottom left corner of the cover page, as shown:

Source: OCR A Level Chemistry Data Sheet

The other important thing to check about the data sheet that you are using is that it is the datasheet for your course. This can be checked at the top of the cover page, where it specifies the courses that it is designed for:

Source: OCR A Level Chemistry Data Sheet

General information and infrared data 

This page is essentially split into two halves:

• The first half contains what is called general information

• The second half contains an infrared spectroscopy data table

General information 

This contains 7 pieces of information about values, constants, conversions and equations that you would be expected to know and be able to use.

1. Molar gas volume

   1. This explains that one mole of a gas will occupy 24.0 dm3 at room temperature and pressure (RTP).

   2. Although this is given in the datasheet, many students just know this value without needing to look it up.

   3. For more information about molar gas volume, see our revision note on the Amount of Substance.

2. Avogadro constant 
   

   1. Avogadro’s constant is the number of particles equivalent to the relative atomic, molecular or formula mass of a substance.

   2. The Avogadro constant is written as N_A and has a value of 6.02 x 10²³ mol^-1.

      1. This is the same value as you may have previously used in your previous OCR GCSE studies.

      2. It is important that you use this value in questions - some students may use a more accurate value, which should not be penalised in an exam but it is always best to use the value given in the datasheet!

   3. For more information about the Avogadro constant, again, see our revision note on the Amount of Substance

3. Specific heat capacity of water
   

   1. The specific heat capacity of water is the amount of energy needed to increase the temperature of 1 g of water by 1 ^oC.

   2. The OCR exam board are specific about the use of the specific heat capacity of water, which they write as c and has a value of 4.18 J g^-1 K^-1.
      

      1. Be careful as you may have used a less precise value in your previous studies, depending on which exam board you studied.

      2. The specific heat capacity of water, 4.18 J g-1 K-1, is an important value in calorimetry experiments and determining enthalpy changes, which is one of your practical assessment group experiments (PAG3).

   3. For more information about the specific heat capacity of water, see our revision notes on Calorimetry and Determination of Enthalpy Changes.

4. Ionic product of water
   

   1. The ionic product of water is the specific equilibrium constant for the dissociation of water molecules into protons and hydroxide ions.

   2. It is written as Kw and has a value of 1.00 × 10−14 mol2 dm−6 at 298K.

   3. For more information about the ionic product of water, see our revision note on K_a, pH & K_w

5. 1 tonne in g
   

   1. This shows that 1 tonne is 106 g

6. Arrhenius equation 
   

   1. The Arrhenius equation shows the relationship between the rate constant (k), temperature (T) and activation energy (Ea).

   2. The data sheet gives two versions of the Arrhenius equation:

      1. k = Ae(-Ea / RT)

      2. ln k = −Ea / RT + ln A, which can be used in conjunction with an Arrhenius plot to calculate the activation energy of a reaction.
         

   3. Application of the Arrhenius equation is one of the more challenging mathematical themes in A level chemistry.

   4. For more information about the Arrhenius equation, see our revision note on The Arrhenius Equation

7. Gas constant
   

   1. The gas constant is sometimes known as the ideal gas constant and is a physical constant that appears in the ideal gas law, PV = nRT.

   2. It is written as R and has a value of 8.314 J mol-1 K−1.

   3. It is very likely that you will use the gas constant in an ideal gas law question in your exams.

   4. For more information about the gas constant, see our revision note on The Ideal Gas Equation.
      

Infrared spectroscopy data table

A relatively comprehensive set of infrared absorption data is given in the datasheet. It is called  “characteristic infrared absorptions in organic molecules” and presented in the following table:

Characteristic infrared absorptions in organic molecules

Source: OCR A Level Chemistry Data Sheet

Generally, you will be required to use infrared data to:

• Identify an organic compound from a selection of given compounds

  • These are typically one mark multiple choice questions.

  • For example, question 7 in the June 2022, H432/03 exam paper on synthesis and analytical techniques.

  • The question asks you which compound could have produced the following infrared spectrum.

Source: OCR H432/02 Synthesis and Analytical Techniques exam paper (June 2022)

• A: H2C=CHCH2CH2OH

• B: CH3COOCH2CH3

• C: H2NCH2COOCH3

• D: (CH3)2CHCONH2 

• It cannot be compound A as there is no peak at 1620 - 1680 cm-1 for a C=C bond and no peak at 3200 - 3600 cm-1 for an alcoholic OH bond.

• It cannot be compounds C or D as there is no peak at 3300 - 3500 cm-1 for an N-H bond.

• It is compound B because there is a peak at around 1750 cm-1 which corresponds to the carbonyl bond of an ester. The other peak that you would expect for an ester is the C-O bond at 1000 - 1300 cm-1 but this is the fingerprint region and cannot be relied upon.

• Determine the structure of an organic compound, often in conjunction with other data including empirical / molecular formula, chemical tests mass spectra and NMR spectra.

  • For example, question 22 in the October 2020, H432/03 exam paper on synthesis and analytical techniques. 

• Predict the infrared absorption peaks for a given compound.

  • This type of question is less common in OCR exams.

Other exam boards have their own sets of infrared absorption peaks, which are not always the same as the OCR data. So, it is important that you use and quote the specific values given in the OCR A level chemistry data sheet for questions to ensure that you don’t lose easy marks!

For more information about infrared spectroscopy, see our revision note on Infrared Spectroscopy.

13C NMR and 1H NMR chemical shifts

This page is essentially split into 3 sections:

1. 13C NMR chemical shifts relative to TMS

2. 1H NMR chemical shifts relative to TMS

3. Extra notes regarding chemical shifts

13C NMR chemical shifts

OCR has a relatively small number of 13C NMR peaks compared to other exam boards, which are presented as a chart:

Source: OCR A Level Chemistry Data Sheet

The relatively small number of peaks on the 13C NMR chemical shift chart and the clear layout mean that you will be expected to use the specific values shown for relevant peaks.

For more information about 13C NMR spectroscopy, see our revision note on Carbon-13 NMR.

1H NMR chemical shifts

OCR has a similar number of 1H NMR peaks compared to most other exam boards, which are presented as a chart:

Source: OCR A Level Chemistry Data Sheet

Again, the clear layout of the 1H NMR chemical shift chart means that you will be expected to use the specific values shown for relevant peaks. The data sheet only gives information about the potential position of peaks on a 1H NMR spectrum, it does not give any indication about splitting patterns.

For more information about 1H NMR spectroscopy, see our revision note on Proton NMR.

Extra notes regarding chemical shifts

These notes at the bottom of page 3 explain how the chemical shifts may not always appear as expected due to the solvent, concentration and substituents.  For example, a CH bonded to groups that cause shifting such as C-O and C=O may be shifted outside of the ranges suggested in the NMR charts.
The notes also reinforce that the peaks due to protons involved in alcohol O-H bonds and amine N-H bonds are “very variable”, as shown by the block from 0.5 - 12.0 ppm on the 1H NMR chart.

Generally, you will be required to use the 13C and 1H NMR chemical shift data to:

• Identify an organic compound from a selection of given compounds
  

  • These are typically one mark multiple choice questions.

  • For example, question 12 in the June 2019, H432/03 exam paper on synthesis and analytical techniques.

  • The question asks you which compound could have produced the following 13C NMR spectrum.

Source: OCR H432/02 Synthesis and Analytical Techniques exam paper (June 2019)

• A: Propane

• B: 2-Methylbutane

• C: 2-Methylpropan-1-ol 
  D: 2-Methylpropan-2-ol

• It cannot be compounds A or B as the peak at ~73 ppm is beyond the range for alkyl C-C carbons.

• It cannot be compound D as there are three peaks and 2-methylpropan-2-ol is symmetrical, which means that it would only have 2 peaks.

• It is compound C because there is the correct number of peaks AND the peak at ~73 ppm is a C-O carbon which would be present in an alcohol.

• Determine the structure of an organic compound, often in conjunction with other data including empirical / molecular formula, chemical tests mass spectra and infrared spectra.

  • For example, question 21 in the June 2019, H432/03 exam paper on synthesis and analytical techniques. 

• Predict the position of 13C and 1H NMR peaks for a given compound.

  • Like infrared spectroscopy, this type of question is less common in OCR exams - it was more common in exam papers for the previous OCR specification. 

The Periodic Table of the Elements

The inclusion of a periodic table is a relatively standard addition to any datasheet. 

As with most A Level Chemistry periodic tables, the relative atomic mass values are given to 1 decimal place. This is a change from previous periodic tables that you may have used in your GCSE (or equivalent) qualifications. Therefore, you should check your periodic table to ensure that you are using the correct values in your answers so that you don’t miss an easy mark.

For more information about periodic tables, see our article on the OCR A Level Chemistry Periodic Table