The main source of the element magnesium in Australia is the ore magnesite, in which magnesium is present as magnesium carbonate (MgCO₃). (a) Calculate the percentage by mass of magnesium in magnesium carbonate. (b) Magnesium carbonate reacts with aqueous hydrochloric acid according to the reaction MgCO₃(s) + 2HCl(aq) → MgCl₂(aq) + H₂O(l) + CO₂(g) A series of laboratory experiments was set up to study the rate of this reaction under some different conditions. The initial reaction rate was determined by measuring the rate of evolution of CO₂ in a gas syringe as shown in the following diagram.

SSCE VCE Chemistry Chemical Elements: The main source of the element m

The main source of the element magnesium in Australia is the ore magnesite, in which magnesium is present as magnesium carbonate (MgCO₃) - VCE - SSCE Chemistry - Question 1 - 2004 - Paper 1

Question 1

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The main source of the element magnesium in Australia is the ore magnesite, in which magnesium is present as magnesium carbonate (MgCO₃). (a) Calculate the percenta... show full transcript

Worked Solution & Example Answer:The main source of the element magnesium in Australia is the ore magnesite, in which magnesium is present as magnesium carbonate (MgCO₃) - VCE - SSCE Chemistry - Question 1 - 2004 - Paper 1

Step 1

Calculate the percentage by mass of magnesium in magnesium carbonate.

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Answer

To calculate the percentage by mass of magnesium in magnesium carbonate (MgCO₃), we start by determining the molar mass of MgCO₃.

Identify the molar masses:
- Molar mass of Magnesium (Mg): 24.31 g/mol
- Molar mass of Carbon (C): 12.01 g/mol
- Molar mass of Oxygen (O): 16.00 g/mol
Calculate the molar mass of MgCO₃:

$M(MgCO₃) = M(Mg) + M(C) + 3 imes M(O)$ $= 24.31 + 12.01 + (3 imes 16.00)$ $= 24.31 + 12.01 + 48.00$ $= 84.32 ext{ g/mol}$
Calculate the percentage by mass of magnesium:

$ext{Percentage by mass of Mg} = \left( \frac{M(Mg)}{M(MgCO₃)} \right) \times 100$ $= \left( \frac{24.31}{84.32} \right) \times 100$ $\approx 28.8\%$

Thus, the percentage by mass of magnesium in magnesium carbonate is approximately 28.8%.

Step 2

Magnesium carbonate reacts with aqueous hydrochloric acid according to the reaction.

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Answer

The reaction can be analyzed to study its kinetics, and various factors can be examined:

Increased temperature increases the number of collisions...: Increasing the temperature enhances the kinetic energy of particles.
Increasing the concentration of HCl provides more frequent collisions...: Higher concentrations mean more reactants are present in the solution, which leads to a higher probability of collisions between H⁺ ions and MgCO₃.
Increased amount of MgCO₃ increases surface area...: More surface area allows more collisions and hence a more significant reaction rate.

Ultimately, the reaction rate can be influenced by several variables including temperature, concentration of reactants, and surface area of the solid reactants.

The main source of the element magnesium in Australia is the ore magnesite, in which magnesium is present as magnesium carbonate (MgCO₃) - VCE - SSCE Chemistry - Question 1 - 2004 - Paper 1

Worked Solution & Example Answer:The main source of the element magnesium in Australia is the ore magnesite, in which magnesium is present as magnesium carbonate (MgCO₃) - VCE - SSCE Chemistry - Question 1 - 2004 - Paper 1

Calculate the percentage by mass of magnesium in magnesium carbonate.

Magnesium carbonate reacts with aqueous hydrochloric acid according to the reaction.

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