physical sciences

The equation for the combustion of butane gas is given below. 7.1 Define the term activation energy.(2) 7.2 Is the combustion reaction of butane exothermic or endothermic? Give areason for the answer.(2) 7.3 Draw a sketch graph of potential energy versus course of reaction for thereaction above. Clearly indicate the following on the graph: Activation … Read more

The simplified diagram below shows a blast furnace used for the extraction of iron from  iron ore. P represents a reactant added to the blast furnace. Q and R represent  products that leave the blast furnace.  Limestone and coke are added to the blast furnace, as shown in the diagram above. Write down the function … Read more

9.1 Oxidation numbers make it easier to determine whether an element or a  substance is oxidised or reduced during a chemical reaction.  9.1.1 Define the term oxidation with reference to oxidation numbers. (2) 9.1.3 Calculate the oxidation number of oxygen in H2O2. (1)  9.2 Consider the UNBALANCED equation below:   Fe2+(aq) + Cℓ2(g) → Fe3+(aq) + … Read more

When sulphuric acid reacts with water, it ionises in two steps, as shown in the two  balanced equations below.  8.1 Define an acid in terms of the Lowry-Brønsted theory. (2) 8.2 Write down the FORMULA of:  8.2.3 A substance that acts as ampholyte in these reactions (1)  8.3 A few drops of bromothymol blue indicator … Read more

Electronegativity of atoms may be used to explain the polarity of bonds. 2.1 Define the term electronegativity. (2) 2.2 Draw the Lewis diagram of an oxygen difluoride molecule. (2) 2.3 Calculate the electronegativity difference between O and F in oxygendifluoride and predict the polarity of the bond. (2) 2.4 A polar bond does not always … Read more

A barium hydroxide solution, Ba(OH)2(aq), reacts with a nitric acid solution, HNO3(aq),  according to the following balanced equation:  Ba(OH)2(aq) + 2HNO3(aq) → Ba(NO3)2(aq) + 2H2O(ℓ)  The potential energy graph below shows the change in potential energy for this reaction.  7.1 Is this reaction ENDOTHERMIC or EXOTHERMIC? Give a reason for the  answer. (2)  7.2 Use … Read more

6.1 Sodium thiosulphate, Na2S2O3(s), reacts with 200 cm3 of a hydrochloric acid  solution, HCℓ(aq), of concentration 0,2 mol·dm-3 according to the following  balanced equation:  Na2S2O3(s) + 2HCℓ(aq) → 2NaCℓ(aq) + S(s) + SO2(g) + H2O(ℓ)  6.1.1 Define the term concentration of a solution. (2)  6.1.2 Calculate the number of moles of HCℓ(aq) added to the … Read more

The fizz produced when an antacid dissolves in water is caused by the reaction  between sodium hydrogen carbonate (NaHCO3) and citric acid (H3C6H5O7). The balanced equation for the reaction is:  3NaHCO3(aq) + H3C6H5O7(aq) → Na3C6H5O7(aq) + 3CO2(g) + 3H2O(ℓ)  5.1 Write down the FORMULA of the substance that causes the fizz when the  antacid dissolves in … Read more

A learner investigates the relationship between the pressure and volume of an  enclosed DIATOMIC gas at 25°C. He records the volume of the gas for different  pressures in the table below. 4.1 Write down the name of the gas law being investigated. (1) Answer QUESTION 4.2 and QUESTION 4.3 on the attached ANSWER SHEET.  4.4 … Read more