Chemical Reaction and Equation Edexcel

Which equation represents the reaction for which the enthalpy change is the standard enthalpy change of formation, ∆Hf ○, of sodium nitrate, NaNO3?

• 2Na(s) + 2H2O(l) -> 2NaOH(aq) + H2(g)
• Na(s) + 1/2Cl2(g) -> NaCl(s)
• 2NaNO3(aq) -> 2NaNO2(aq) + O2(g)
• Na(s) + ½N2(g) + 1½O2(g) → NaNO3(s)

Which equation represents the reaction for which the enthalpy change, ∆H, is the mean bond enthalpy of the C–H bond?

• A ¼CH4(g) → ¼C(g) + H(g)

• B CH4(g) → C(s) + 2H2(g)

• C CH4(g) → C(g) + 4H(g)

• D CH4(g) → C(g) + 2H2(g)

The bonding in magnesium oxide, MgO, is

• Ionic
• Covalent
• Metallic
• Hydrogen bonding

Magnesium chloride can be made by reacting solid magnesium carbonate, MgCO3, with dilute hydrochloric acid. (a) Write an equation for the reaction, including state symbols.

• MgCO3(s) + 2HCl(aq) -> MgCl2(aq) + H2O(l) + CO2(g)
• MgCO3(aq) + 2HCl(s) -> MgCl2(aq) + H2O(l) + CO2(g)
• MgCO3(s) + 2H2O(l) -> MgCl2(aq) + HCl(g) + CO2(g)
• MgCO3(s) + 2HCl(aq) -> MgCl(aq) + H2O(l) + CO2(g)

Magnesium chloride can be made by reacting solid magnesium carbonate, MgCO3, with dilute hydrochloric acid. (b) Give TWO observations you would make when the reaction is taking place

• Effervescence and formation of a white precipitate
• Bubbling: You would observe bubbles or fizzing as carbon dioxide gas (CO₂) is produced and released from the reaction mixture.

• The solid magnesium carbonate (MgCO₃) would gradually dissolve in the dilute hydrochloric acid (HCl) solution as the reaction proceeds.

• No change in color

For the oxidation of ammonia a NH3 + b O2 oc NO + d H2O the values of the coefficients in the balanced equation are

• A a = 2, b = 3, c = 2 and d = 3

• B a = 4, b = 7, c = 4 and d = 4

• C a = 4, b = 5, c = 4 and d = 6

• D a = 6, b = 7, c = 6 and d = 9

A molecule is

• A a group of atoms bonded by ionic bonds.

• B a group of atoms bonded by covalent bonds.

• C a group of ions bonded by covalent bonds.

• D a group of atoms bonded by metallic bonds.

Oxygen can be prepared using several different reactions. Which of those given below has the highest atom economy by mass?

• A NaNO3 --> NaNO2 + ½O2

• B H2O --> 2oH2O + ½O2

• C Cl2 + H2O --> 2HCl + ½O2

• D PbO2--> PbO + ½O2

Chlorine can be prepared by the reaction between concentrated hydrochloric acid and concentrated sodium chlorate(I). Chlorine is a hazardous substance and the risk due to the chlorine is best lowered by

• A. using a fume cupboard.

• B wearing gloves.

• C wearing goggles.

• D working in groups.

Metallic bonding is best described as the electrostatic attraction between

• A cations and anions.

• B cations and delocalised electrons.

• C nuclei and shared pairs of electrons.

• D nuclei and two electrons from one atom