Why does the element calcium react with water differently than magnesium, potassium and sodium, in a way that calcium looks opaque and cloudy in water and when phenlotphtahein is added it looks bright pink but how come the other elements don't look like that in water? what makes calcium look different in appearance?
When Ca reacts with water the product is Ca(OH)2 and that is less soluble than, for example, NaOH when Na reacts with water. Both will give a bright pink color with phenolphthalein.
The reaction of calcium with water is different compared to magnesium, potassium, and sodium due to several factors. The main reasons why calcium appears opaque, cloudy, and exhibits a bright pink color when phenolphthalein is added are:
1. Reactivity: Calcium is less reactive with water compared to the other metals mentioned. This means that calcium reacts with water more slowly, resulting in a less violent reaction. This characteristic allows calcium to react in a more controlled manner, leading to the appearance of an opaque and cloudy solution.
2. Formation of Calcium Hydrate: When calcium reacts with water, it forms calcium hydroxide, which is sparingly soluble. As a result, it precipitates out of solution, causing the solution to appear cloudy. This precipitation occurs due to the low solubility of calcium hydroxide in water.
3. Formation of Calcium Phenolate: The bright pink color observed when phenolphthalein is added to the solution is due to the formation of calcium phenolate. Phenolphthalein is an indicator that changes color in the presence of a base, and calcium hydroxide acts as a base. The reaction between phenolphthalein and calcium hydroxide forms calcium phenolate, giving the solution its pink hue.
On the other hand, metals like magnesium, potassium, and sodium react more vigorously with water. Their reactivity leads to the formation of hydroxides that are more soluble, resulting in a clear solution. These hydroxides do not precipitate out of solution like calcium hydroxide does, hence their different appearance in water.
The difference in the reaction of calcium with water compared to magnesium, potassium, and sodium is primarily due to the differences in their reactivity and the formation of different products during the reaction.
When calcium reacts with water, it undergoes a vigorous and exothermic reaction. Calcium reacts with water molecules to produce calcium hydroxide (Ca(OH)2) and hydrogen gas (H2). The reaction is highly exothermic, meaning it releases a large amount of heat. Additionally, the calcium hydroxide produced is sparingly soluble in water, which means it does not dissolve easily.
The white cloudy appearance observed when calcium reacts with water is due to the formation of calcium hydroxide, which appears as a precipitate. The precipitate scatters light, causing the water to have an opaque or cloudy appearance.
When phenolphthalein is added to the calcium-water mixture, it turns bright pink. Phenolphthalein is an indicator that changes color in the presence of bases. Calcium hydroxide is a base, and its formation during the reaction with water causes the solution to become basic, turning the phenolphthalein pink.
On the other hand, magnesium, potassium, and sodium react with water in a less vigorous manner. Magnesium reacts with water to produce magnesium hydroxide, but it does so at a slower rate and with less heat generation compared to calcium. Magnesium hydroxide is also a sparingly soluble compound but does not form as much precipitate as calcium hydroxide. As a result, the appearance and cloudiness observed in the magnesium-water reaction are less pronounced compared to calcium.
Potassium and sodium undergo even milder reactions with water, producing potassium hydroxide and sodium hydroxide, respectively. These hydroxides are highly soluble in water and do not form significant precipitates, resulting in a clear solution. Therefore, their reactions with water do not exhibit the same cloudiness or opacity as observed with calcium.
In summary, the difference in appearance and reactivity among calcium, magnesium, potassium, and sodium when reacting with water is attributed to their varying reactivity levels and the formation of different products during the reaction.