Chemistry assignment

Term: 2019 Summer

Assignment 2

Name: ___________________________ Time: _______________ Total: _________

1.Single Chioce:

(i) In the solution of the following groups , the ions in which group will generate precipitation after adding HCl solution.

A. Hg22+, Pb2+                 B. Be2+, Sn2+ C. Ag+, Cu2+           D. Ba2+,Cd2+

Answer:________________________

(ii) The environment performs 10kJ work on the system, and the system loses 5kJ of heat to the environment, the internal energy of the system changes : ?。

(A) -15kJ (B) 5kJ (C) - 5kJ (D) 15kJ

Answer:________________________

(iii) The following substances can not release hydrogen in the presence of water?

A. B2H6 B. CaH2 C. SiH4 D. N2H4

Answer:________________________

2. Characterize the following compounds as soluble or insoluble in water: (a) Ca3(PO4)2, (b)Mn(OH)2, (c)AgClO3, (d)K2S, (e)CaCO3, (f) ZnSO4,(g) Hg(NO3)2, (h) HgSO4, (i) NH4ClO4

Answer:

Soluble:

Insoluble:

3. On the basis of oxidation number considerations, one of the following oxides would not react with molecular oxygen: NO, N2O, SO2, SO3, P4O6. Which one is it? Why?.

4. Acetic acid (CH3COOH) is an important ingredient of vinegar. A sample of 50.0 m L of a commercial vinegar is titrated against a 1.00 M NaOH solution. What is the concentration (in M) of acetic acid present in the vinegar if 5.75 mL of the base were required for the titration?

5. Propane (C3H8) burns in oxygen to produce carbon dioxide gas and water vapor. (a) Write a balanced equation for this reaction. (b) Calculate the number

of liters of carbon dioxide measured at STP that could be produced from 7.45 g of propane.

6. Water is an extremely weak electrolyte and therefore cannot conduct electricity. Why are we often cautioned not to operate electrical appliances when our hands are wet?