Chemistry Answers

A gas occupies a volume of 31.0L at 17.0⁰C. If the gas temperature rises to 34.0⁰C at constant pressure, would you expect the volume to double to 2.0L?

A sample of a gas occupies 75.0mL at 0.400atm. If the temperature remains constant, a.)what volume would the gas occupy at 4.00atm? b.) How about 0.00400 atm? (Note: 1atm = 1.01325 x10⁵ Pa)

A 1.68 gram sample of CaCO₃ (100.09 g/mol) is placed in a 109 mL flask and dissolved in HCl, calculate the resulting molarity of the calcium ion.

What is the percentage composition of Na2SO4?

Suppose you have two containers, one containing a dilute acid and the

other a dilute base, but there are no labels on them. Describe how you

could use red cabbage to determine which solution is which.

How many grams of CuCl2·2H2O are needed to prepare 0.500 L of solution containing 0.250 M Cl-(aq)?

What is the molarity of Na+(aq) in a solution containing 0.250 M Na2SO4 (aq)?

How many moles of NaCl are contained in 328.0 mL of 2.81 M NaCl (aq)?

Zinc oxide can be produced by the following reaction:

2 Zn (s) + O2 (g) → 2 ZnO (s)

There are many uses for ZnO, but one is a heat-reflective coating on windows (thus lowering cooling demands in hot climates). This coating requires a thin layer (approximately 40-50 µm thick) of zinc oxide. 

  Assume that this thin film uses 1.9x1020 Zn atoms per cm2 of surface. How many grams of ZnO are added to a window that has an area of 5500 cm2?

In older airbags, sodium azide, NaN3, was used as a source of nitrogen gas to rapidly inflate the airbag. This practice was mostly discontinued due to the high toxicity of sodium azide. The reaction of interest is 2 NaN3 (s) → 2 Na (s) + 3 N2 (g) 

How many grams of N2 are produced if a 35.0 g charge of NaN3 decomposes?

Considering the same prompt, suppose I wanted to inflate a 125 L airbag with N2 (g) to a density of 0.450 g N2 / L. This is more or less a typical value for the passenger airbag. To do so I would need Answer g of N2 (g).

Considering the reaction for the decomposition of sodium azide, this would require a Answer g of NaN3.

This same process would produce Answer g Na (s). Keep in mind that sodium metal is highly reactive, and that a dose of ~ 2 g of sodium azide can be lethal. Sodium azide is still used in some airbags, but it has largely been phased out due to the legitimate safety concerns.