Chemistry Flashcards

What is the molarity of a solution containing 58.5 g of NaCl dissolved in 1 liter of solution? (Molar mass of NaCl = 58.5 g/mol)

Answer: 1 M

Molarity = moles of solute / liters of solution. Moles of NaCl = 58.5 g / 58.5 g/mol = 1 mol. Molarity = 1 mol / 1 L = 1 M.

According to Le Chatelier's Principle, what happens when pressure is increased on the reaction N₂ + 3H₂ ⇌ 2NH₃?

Answer: Equilibrium shifts to the right (toward fewer moles of gas)

Increasing pressure shifts equilibrium toward the side with fewer moles of gas. The left side has 4 moles (1 + 3) while the right has 2 moles, so equilibrium shifts right, producing more NH₃.

What type of reaction is: 2Na + Cl₂ → 2NaCl?

Answer: Synthesis (combination)

This is a synthesis (combination) reaction where two reactants (sodium and chlorine) combine to form a single product (sodium chloride).

What is the oxidation state of sulfur in H₂SO₄?

Answer: +6

In H₂SO₄: H is +1 (×2 = +2), O is -2 (×4 = -8). For the compound to be neutral: +2 + S + (-8) = 0, so S = +6.

What distinguishes an exothermic reaction from an endothermic reaction?

Answer: Exothermic reactions release heat energy to surroundings, endothermic reactions absorb heat

Exothermic reactions release energy (negative ΔH) and increase surrounding temperature, while endothermic reactions absorb energy (positive ΔH) and decrease surrounding temperature.

How many valence electrons does oxygen have?

Answer: 6

Oxygen is in Group 16 (VIA) of the periodic table, so it has 6 valence electrons in its outer energy level (electron configuration: 2, 6).