calculate the concentration of the following acid and base solutions (in %m/v) and answer the question: Which one of the two is more corrosive?
1. Solution A: 10 g of alkali in 250 cm³ of water.
Solution B: 20 g of alkali in 500 cm³ of water.
(Please note: 1 cm³ = 1 mL)
2. Solution A: 2.5 g of acid in 50 mL of water
Solution B: 1 g of acid in 10 mL of water.
Answers
The variation of solubility with temperature has been measured for a wide range of compounds, and the results are published in many standard reference books. Chemists are often able to use this information to separate the components of a mixture by fractional crystallization, the separation of compounds on the basis of their solubilities in a given solvent. For example, if we have a mixture of 150 g of sodium acetate (CH3CO2Na) and 50 g of KBr, we can separate the two compounds by dissolving the mixture in 100 g of water at 80°C and then cooling the solution slowly to 0°C. According to the temperature curves in Figure 7.3, both compounds dissolve in water at 80°C, and all 50 g of KBr remains in solution at 0°C. Only about 36 g of CH3CO2Na are soluble in 100 g of water at 0°C, however, so approximately 114 g (150 g − 36 g) of CH3CO2Na crystallizes out on cooling. The crystals can then be separated by filtration. Thus fractional crystallization allows us to recover about 75% of the original CH3CO2Na in essentially pure form in only one step.
Explanation:
5. In a circle with centre C, take points and o) on the circle such that PO - radius of the
circle. Join CP and Co. Measure PCO, Is PCO an equiangular triangle?