General Chemistry Answers

Suppose we have a sample of ammonia gas (NH3) with a volume of 7.0 mL at a pressure

of 1.68 atm. The gas is compressed to a volume of 2.7 mL at a constant temperature. Use

the ideal gas law to calculate the final pressure.

Calculate the standard enthalpies of the following reactions from the standard molar enthalpies of formation of the reactants and products. Identify if the reaction is endothermic or exothermic.

1.   2NH₃ (g) + 3N₂O (g)                   4N₂ (g) + 3H₂O (l)            ΔH_rxn = __________

2.   CaO₃(s)               CaO (s) + CO₂(g)                                ΔH_rxn = __________

3.   C (graphite) + O₂(g)             CO₂(g)                                 ΔH_rxn = __________

If a saturated boric acid solution is made (by dissolving boric acid in warm water until it no longer dissolves) - How much boron is in 1teaspoon of saturated solution.

Commercial brass, an alloy of Zn and Cu, reacts with hydrochloric acid to form zinc chloride and hydrogen gas. Copper does not react with HCl. When 0.6503 g of a brass sample is reacted with excess HCl, 0.1087 g ZnCl2 is eventually isolated. What is the percent (%) composition of brass by mass?

Arrange the following based on their viscosity

Cooking oil

Milk

Rubbing Alcohol

Shampoo

Lamp Oil

Honey

Dishwashing Soap

Corn Syrup

Maple Syrup

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An element x with atomic number 29 has two isotopes Y and Z have 34 and 38 neutrons respectively. Calculate the 

a.mass number of each isotope, and hence, write their nuclear symbols.

b.percentage abundance of each isotope, if the relative atomic mass of element x is 63.5.

`Batrachotoxin (C₃₁H₄₂N₂O₆) is the most potent non-peptide (we'll learn what that means in Lesson 7) based poison known. It gained fame though its use in poison darts made from frog excretions. The frogs themselves don't produce the toxin directly, but through digestion of Melyrid beetles the frogs eat. Suppose you are trekking through the rainforest and discover an even more potent toxin that has the same empirical formula as batrachotoxin. If the molar mass of this new poison is 3,232.02 g/mol, what is its molecular formula?

If 100mL of water contains 5 grams of NaCl molecular mass = 58.8g/mol what is the molarity of the solution in moles/L?

For the following reaction, 5.59 grams of oxygen gas are mixed with excess carbon (graphite). The reaction yields 7.10 grams of carbon dioxide.

carbon (graphite) ( s ) + oxygen ( g )  carbon dioxide ( g )

What is the theoretical yield of carbon dioxide? ____ grams

What is the percent yield for this reaction? ____ %