please help me question 4 concentration of all substances when new equilibrium i

Question

please help me question 4

concentration of all substances when new equilibrium is established. Question 4: The product solubility K) of Cas(POsh is 2xlo- at 25°C Calculate the solubility of this substance. Mix 150 ml of CaCl: 10-'M and 250 ml of NasPO, 10-M. is there the precipitate and how much? Question 5: The amount of heat will be released or absorbed when dissolve I mol of CuS0 1 mol of Cuso, H0 and 1 mol of CuSO, 5H:0 in 800 mol water are -15.90-9.33 and 2.80 kcal. respectively. Calculate enthalpy change of below processes CuSO,H20 (1) CuSO CuSO,H2O Cuso, ? ? ? CuS04-5H3O Cuso, 5H3O (2) 3)

Explanation / Answer

4.

(a)

Solubility equaion is,

Ca3(PO4)2 (s) = 3 Ca2+ (aq.) + 2 PO42- (aq.)

S                         3S                       2S

Ksp = [Ca2+]3[PO42-]2

2 * 10-33 = (3S)3(2S)2

2 * 10-33 = 27 * S3 * 4 * S2

S5 = 1.85 * 10-35

S = (1.85 * 10-35)(1/5)

S = Solubility of Ca3(PO4)2 = 1.13 * 10-7 M

(b)

Molarity of Ca2+ = 10-3 * 150 / (150 + 250) = 0.000375 M

Molarity of PO43- = 10-2 * 250 / (150 + 250) = 0.00625 M

NOW,

Qsp = [Ca2+]3[PO42-]2

Qsp = (0.000375)3(0.00625)2

Qsp = 2.06 * 10-15

Since Qsp > Ksp, precipitation occurrs.

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