Practice Paper 1A (HL IB Chemistry)

The atomic number of an element gives the number of protons in the nucleus which is also equal to the number of electrons. Which statement explains why atoms are neutral?

The diagram shows three orbitals labelled 1, 2 and 3. 

What is the correct label for each orbital?

Ethanoic acid has the formula CH₃COOH. How many carbon atoms are present in
0.1 mol of ethanoic acid?

0.96 g of hydrogen gas is contained in a sealed vessel of volume of 7.0 × 10⁻³ m³ at a temperature of 303 K.

Assume the gas behaves as an ideal gas.

What is the pressure of the vessel in Pa?

Which of the following compounds has both covalent and ionic bonds?

Silver and iodine are both shiny crystalline solids.

Which forces exist between neighbouring iodine molecules in solid iodine and particles in solid silver?

Which of the following molecules has the biggest overall dipole?

 The electronegativity of four elements are given below 

N = 3.0       H = 2.1       F = 4.0      P = 2.1      

 What is the correct order of polarity for the following compounds

Which of the following statements about 2-chloropropene, CH₂C(Cl)CH₃ is correct?

Which of the following species has the highest melting point?

A binary compound is plotted on a triangular bonding diagram. The electronegativity values for each element are 1.6 and 3.4.

Which estimate for the percentage ionic and percentage covalent character in the compound is correct?

The Period 4 elements gallium (Ga), germanium (Ge), arsenic (As) and selenium (Se) are the elements directly below aluminium, silicon, phosphorus and sulfur in the Periodic Table.

The properties of each Period 4 element resemble those of the Period 3 element directly above it.

Which period 4 elements form oxides that dissolve in water to give an acidic solution?

Which of the compounds shown below is likely to have a fragment at m/e = 45 in its mass spectrum?

A student opens a freezer in their lab to remove a test tube containing an oxide of a Period 3 element. The oxide is a solid and forms a solution with a low pH when dissolved in water. 

Identify the element.

The x-axis of the graph below is the atomic number of the elements in Period 3.

Which variable could represent the y-axis?

What is the correct equation for the complete combustion of ethane? 

Chlorine has two isotopes ³⁵Cl and ³⁷Cl.  Assuming in the molecule C₄H₆Cl₄ there is only one hydrogen and one carbon isotope, how many molecular ion peaks will be seen in its mass spectrum?

The infrared spectrum below shows an unknown compound.

Which compound could have produced the infrared spectrum?

An experiment was carried out to determine the approximate value for the molar enthalpy change of neutralisation. 

75 cm³ of 3.00 mol dm^–3 hydrochloric acid was placed in a polystyrene beaker of negligible heat capacity. Its temperature was recorded, and then 75 cm³ of 3.00 mol dm⁻³ potassium hydroxide at the same temperature was quickly added, and the solution stirred. 

The temperature rose by 14 °C. The resulting solution may be considered to have a specific heat capacity of 4.18 J g^-1 K^-1. 

What is the value for ΔH?

Titanium occurs naturally as the mineral rutile, TiO₂. One possible method of extraction of titanium is to reduce the rutile by heating with carbon. 

TiO₂ (s) + 2C (s) → Ti (s) + 2CO (g) 

The standard enthalpy changes of formation of TiO₂(s) and CO(g) are –890 kJ mol^-1 and –110.5 kJ mol^-1 respectively. 

What is the standard enthalpy change of the extraction of titanium?

Which compound has an M_r of 84.18 and will react with HBr to give a product with an M_r of 165.09?

The combustion of ethanol (C₂H₅OH) is increasingly being used to fuel cars. The combustion reaction is shown below.

C₂H₅OH (l) + 3O₂ (g) → 2CO₂ (g) + 3H₂O (l) 

• The standard enthalpy change of formation of carbon dioxide is a kJ mol^–1.
• The standard enthalpy change of formation of water is b kJ mol^–1.
• The standard enthalpy change of formation of ethanol is c kJ mol^–1. 

What is the standard enthalpy change of combustion for ethanol?

Ethene is produced according to the following gas-phase synthesis:

2C (s)  + 2H₂ (g) → C₂H₄ (g) 

Thermodynamic data for the components of this equilibrium are

The free energy change for this reaction at 298 K is:

Excess aqueous cold sodium hydroxide is reacted with 0.10 mol of chlorine gas, Cl₂. One of the products is a compound of sodium, oxygen and chlorine.

What mass of the product is formed?

The oxidation of butadiene, CH₂=CHCH=CH₂, using air or oxygen, produces the molecule crotonaldehyde, CH₃CH=CHCHO.

One method of oxidation is to pass a mixture of butadiene and oxygen through a hot aqueous solution of palladium(II) ions, Pd²⁺(aq), which catalyse the reaction.

Which statement about the action of the Pd²⁺(aq) ions is not correct?

The energies of the reactants, the products and the transition state of a reaction are shown in the reaction pathway diagram below.

Which expression correctly represents how to calculate the activation energy of the forward reaction?

The dissociation of gas X₂Y₄ into XY₂ is represented in the equation below:

X₂Y₄ (g)  ⇌  2XY₂ (g)          = +60 kJ mol^-1 

At constant pressure, if the temperature of the equilibrium mixture of the gases is increased, will the volume of the mixture increase or decrease and why?

1 dm³ of gas X and 1 dm³ of gas Y are kept at the same temperature and pressure.

The speed of the molecules is plotted against the fraction of molecules with that speed. From the graph what can be said about the two gases?

The reaction between nitrogen and hydrogen produces ammonia gas:

N₂ (g) + 3H₂ (g)    2NH₃ (g)

If the equilibrium constant for the reaction is x, what is the equilibrium constant for the following reaction?

2N₂ (g) + 6H₂ (g)    4NH₃ (g)

The dotted-line curve on each graph below represents the corresponding distribution for a gas at 300 K.

Which solid-line curve most accurately represents the distribution of molecular energies in the same gas at 500 K?

The following reaction occurs between concentrated sulfuric and nitric acids.

H₂SO₄ + HNO₃ ⇋  H₂NO₃⁺ + HSO₄^-

Identify the two species which are acting as Brønsted–Lowry bases.

The aromatic compound phenol, C₆H₅OH, behaves as a weak acid, due the presence of a hydroxyl group on the benzene ring. What is the correct formula of the conjugate base formed when phenol dissociates?

Four reactions are shown below. In which reaction is the species shown in bold acting as an oxidising agent?

In which compound are there two different elements with the same oxidation number?

Ethane reacts with chlorine in the presence of ultraviolet light to form trichloroethane and hydrogen chloride.

The reaction proceeds via free radical substitution involving initiation, propagation and termination steps.

Which propagation equation is involved in the free radical reaction to form trichloroethane?

Ethene reacts with steam in the presence of sulfuric acid.

C₂H₄  +  H₂O →  CH₃CH₂OH

What type of reaction is this?

In the hydrolysis of bromoethane by aqueous sodium hydroxide, what is the nature of the attacking group and of the leaving group?

Which compound is produced in the reaction between pent-2-ene and steam?

Copper forms the complex [CuCl₄]^2-. Which statements are correct for this complex?

1.   The complex has a tetrahedral shape
2.   The copper ion has a charge of +2
3.   The copper ion acts as a Lewis base