Chemistry Answers

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?

Draw the resonance structure of cyanate ion

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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Fr+CuSO4

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?

Other than hydrogenation of benzene, take three reactions in which benzene reacts differently than the hypothetical 1,3,5-cyclohexatriene and explain the mechanism and reasons behind this

mechanism