Question

Answer the following questions from the given solubility curve. 150 KI 140 130 120 110 NaNO3 100 90 KNO3 Grams of solute per 100 g H,0 80 70 60 NH3) NHACI 50 KCI Naci 40 30 20 KCIÓ: 10 -Ce2(SO4)3 0 0 10 20 30 40 50 60 70 80 90 100 Temperature (°C) (a) Define solution. Explain with the substance having a trigonal shape from the above solubility curve. (2 marks) (b) Which factor of the solubility, decrease the solubility of the substance having a trigonal shape? (1 mark) (c) A 20 g of potassium chloride make an unsaturated solution in 100 g of water at

Answer 1

Ans to Qsn No(a):

A solution can be defined as a homogeneous mixture of two or more substances. Here homogeneous mixture means that type of mixture in which the proportions of the contents are same throughout the whole mixture.

Among the molecules given in the solubility curve, NH​​3 has trigonal pyramidal shape.

Here, we've seen that the solubility curve gives the amount (grams) of the solute dissolved in per 100 grams of H​​​​​​2​​​​​O with the rise in temperature.

From the solubility curve of NH​​​​​3 it is observed that the solubility decreases with the rise in temperature. The solubility of NH​​​​​3 is high at zero degree Celsius, almost 90g in 100g of water at saturated state. But as the temperature increases it is declining and becomes alsomt 8g in 100g of water at saturated state.

Ans to Qsn No(b) :

The molecule having a trigonal shape among the mentioned substances in the solubility curve is ammonia (NH​​​​​3). From the solubility curve it is seen that the solubility of ammonia decreases with increase in temperature. The high solubility of ammonia at low temperature is due to the strong hydrogen bonding with water molecule (Hydrogen bonding is shown in the image below). Basically hydrogen bonding is the partical intermolecular attraction between an electron rich atom(like Nitrogen, Oxygen, Fluorine etc.) with hydrogen atom. As the temperature is increased the hydrogen bonds will be broken apart. Therefore the binding between ammonia and water becomes weaker and weaker. Due to this factor the solubility of the substance having a trigonal share is decreased.

Hydrogen bonding between ammonia and water molecules it Hoocano •H :0- HecoN Pro It H It H

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