AQA AS Chemistry paper 2 EXAM WITH QUESTIONS AND VERIFIED ANSWERS LATEST UPDATE 2023
Define Relative Atomic Mass (Ar) [1] - ANSWER-the average mass of an element÷ 1/12th the mass of a C12 atom
Define Relative Molecular/Formula Mass (Mr) [1] - ANSWERAverage mass of one molecule ÷ 1/12th the mass of a C12 atom
What is meant by the Avogadro constant? [1] - ANSWER-The number of atoms in 12g of carbon.
Give the formula for moles. [1] - ANSWER-moles= mass÷Mr
Give the formula for concentration in mol/dm³ [1] - ANSWERconcentration = moles÷volume
State the Ideal Gas Equation, what each symbol represents and the units for each symbol. [9] - ANSWER-PV= nRT
where... P= Pressure measured in Pa V= Volume measured in m³ n= number of moles R= The molar gas constant- 8.31JK^-1mol^-1 T= Temperatures measured in K
Define Empirical Formula [1] - ANSWER-The simplest wholenumber ratio of atoms of each element in a compound.
Define Molecular Formula [1] - ANSWER-The actual number of atoms of each element in a compound.
What are the four state symbols? [4] - ANSWER-Solid (s), liquid (l), gas (g), aqueous solution (aq)
Describe how to perform a titration. [5] - ANSWER-1. Fill a burette with the acid of known concentration, 2. Accurately measure 25cm³ of the alkali solution using a pipette and transfer it to a conical flask. 3. Add a few drops of a suitable indicator to the alkali. eg phenolphthalein. 4. Slowly add the acid from the burette into the conical flask, swirling constantly. As soon as the indicator changes colour the solution has turned neutral so stop adding the acid. 5. Record the volume of acid added. 6. Repeat the process until you achieve concordant results. The mean of these results is used to calculate the average titre.
State the formula for percentage atom economy. [1] - ANSWER-
State the formula for percentage yield. [1] - ANSWER-
Describe how to make up a standard solution [7] - ANSWER-1. Weigh the sample bottle containing the solid on a balance.
2. Transfer solid to a beaker and reweigh the sample bottle. 3. Record the difference in mass. 4. Add distilled water and stir with a glass rod until the solid has dissolved. 5. Transfer to a volumetric flask with washings. 6. Makeup to the 250cm³ mark with distilled water. 7. Shake flask.
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