Calcium carbonate is insoluble in water. Name two substances that when mixed in solution, will form a precipitate of calcium carbonate. Explain why is it the two substances that you have chosen.
why does magnesium chloride cannot be prepared in the lab by the reaction of dilute sulfuric acid to give salt magnesium sulfate? Instead of magnesium, magnesium carbonate and magnesium oxide?
You need to have two salts that are soluble, one needs to be a soluble calcium salt. A good choice here is the nitrate as all nitrates are soluble. The other needs to be a soluble carbonate salt. The solubility of the carbonates increases as you go down Group 1, so I would avoid lithium carbonate. Caesium carbonate is very soluble.
"why does magnesium chloride cannot be prepared in the lab by the reaction of dilute sulfuric acid to give salt magnesium sulfate?" I don't understand??
To form a precipitate of calcium carbonate, two substances that can be mixed in solution are calcium chloride and sodium carbonate. This reaction occurs because calcium ions (Ca2+) from calcium chloride react with carbonate ions (CO32-) from sodium carbonate to form calcium carbonate (CaCO3), which is insoluble in water.
The balanced equation for this reaction is:
CaCl2 + Na2CO3 → CaCO3 + 2NaCl
When the two substances are mixed, calcium carbonate precipitates out of the solution as a solid, while sodium chloride remains dissolved. The formation of a solid precipitate indicates that calcium carbonate is insoluble in water.
Regarding the second question, in the lab, magnesium chloride cannot be prepared by the reaction of dilute sulfuric acid to give magnesium sulfate because magnesium chloride is highly soluble in water.
When magnesium reacts with dilute sulfuric acid, the most common reaction that occurs is the formation of magnesium sulfate:
Mg + H2SO4 → MgSO4 + H2↑
In this reaction, the magnesium ions (Mg2+) from magnesium react with the sulfate ions (SO42-) from sulfuric acid to form magnesium sulfate (MgSO4) and hydrogen gas (H2) is released.
On the other hand, magnesium carbonate (MgCO3) and magnesium oxide (MgO) cannot be formed by the reaction of magnesium with dilute sulfuric acid because they are not soluble in water and thus do not react with the acid to form soluble salts.
To determine two substances that can form a precipitate of calcium carbonate when mixed in a solution, we need to consider chemicals that contain calcium ions (Ca2+) and carbonate ions (CO32-). When these ions combine in a solution, they can react to form an insoluble compound, which in this case is calcium carbonate.
One substance that can be used is calcium chloride (CaCl2). When calcium chloride is dissolved in water, it dissociates into calcium ions (Ca2+) and chloride ions (Cl-). When a solution containing carbonate ions (CO32-) is added to the calcium chloride solution, the calcium ions and carbonate ions combine to form a precipitate of calcium carbonate.
Another substance that can be used is sodium carbonate (Na2CO3). Sodium carbonate dissociates in water to produce carbonate ions (CO32-) and sodium ions (Na+). When a solution containing calcium ions (Ca2+) is added to the sodium carbonate solution, a reaction occurs, resulting in the formation of a precipitate of calcium carbonate.
The choice of these two substances is based on the solubility rules. Calcium salts are generally insoluble, and carbonates are also insoluble except for certain alkali metals and ammonium compounds. Therefore, adding a compound containing calcium ions and a compound containing carbonate ions will result in the formation of a precipitate of calcium carbonate.
Now, moving on to your second question about the reaction between dilute sulfuric acid and magnesium to produce magnesium chloride. Unlike metals such as zinc or iron, magnesium does not react with dilute sulfuric acid to produce its chloride salt (magnesium chloride). Instead, it reacts with sulfuric acid to form magnesium sulfate (MgSO4), water (H2O), and hydrogen gas (H2).
The reaction between magnesium and dilute sulfuric acid is as follows:
Mg (s) + H2SO4 (aq) → MgSO4 (aq) + H2 (g)
Magnesium reacts with the sulfuric acid to produce magnesium sulfate salt and simultaneously releases hydrogen gas. This is due to the reactivity series of metals, where magnesium is higher than hydrogen. However, it is worth noting that magnesium chloride can be prepared through other methods, such as the reaction between magnesium oxide or magnesium carbonate with hydrochloric acid:
Magnesium oxide:
MgO (s) + 2HCl (aq) → MgCl2 (aq) + H2O (l)
Magnesium carbonate:
MgCO3 (s) + 2HCl (aq) → MgCl2 (aq) + CO2 (g) + H2O (l)
In these reactions, magnesium oxide (MgO) or magnesium carbonate (MgCO3) reacts with hydrochloric acid (HCl) to form magnesium chloride (MgCl2), water (H2O), and carbon dioxide gas (CO2) in the case of magnesium carbonate.
Overall, the choice of reaction to prepare magnesium chloride depends on the starting materials available and the desired end-products.