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CH2 HW


2.7 The diameter of a neutral helium atom is about 1 × 102 pm. Suppose that we could line up helium atoms side by side in contact with one another. Approximately how many atoms would it take to make the distance from end to end 1 cm?


2.15 For each of these species, determine the number of protons and the number of neutrons in the nucleus:

HW Chapter 03

3.89
Hydrogen fluoride is used in the manufacture of Freons (which destroy ozone in the stratosphere) and in the production of aluminum metal. It is prepared by the reaction
In one process 6.00 kg of CaF2 are treated with an excess of H2SO4 and yield 2.86 kg of HF. Calculate the percent yield of HF

HW　ＣＨ４

1. Give the oxidation number of the underlined atoms in the following molecules and ions: (a) ClF, (b) IF7, (c) CH4, (d) C2H2, (e) C2H4, (f) K2CrO4, (g) K2Cr2O7, (h) KMnO4

2. Describe how to prepare 1.00 L of 0.646 M HCl solution, starting with a 2.00 M HCl solution.

3. Calculate the concentration (in molarity) of a NaOH solution if 25.0 mL of the solution are needed to neutralize 17.4 mL of a 0.312 M HCl solution.


CH5

1.A compound has the empirical formula SF4. At 20°C, 0.100 g of the gaseous compound occupies a volume of 22.1 mL and exerts a pressure of 1.02 atm. What is its molecular formula?
2.A mixture of gases contains CH4, C2H6, and C3H8. If the total pressure is 1.50 atm and the numbers of moles of the gases present are 0.31 mole for CH4, 0.25 mole for C2H6, and 0.29 mole for C3H8, calculate the partial pressures of the gases.
3.What’s the working principle of a MFC and Pressure gage sensor?

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