What are valence electrons and how is valence electron count depicted on the periodic table for a given group?

Which of the following chemical equations (numbered 1 – 3) depict a weak acid? Reaction 1: HCl → H+ (aq) + Cl− (aq) Reaction 2: HC2H3O2 ⇌ H+ (aq) + C2H3O2− (aq) Reaction 3: NH3(aq) + H + (aq) ⇌ NH4 + (aq) [Hint: Firstly, how do you identify a compound as an acid?]

Convert 36.0 cubic centimeters (cm3) to cubic inches (in3).  Note, there are 2.54 cm per inch.  [HINT: Did your units cancel correctly?]

What is the pH of a 2.5 M solution of acetic acid at equilibrium? (Balanced eq: HC2H3O2(aq) + H2O(l) + ⇌ H3O+(aq) + C2H3O2−(aq);  Ka of HC2H3O2 is 1.8 × 10−5 [Hint: What is the definition of pH?]

A 44.5 liter gas cylinder is filled with oxygen gas (O2) at a pressure of 2.00 atm and temperature of 25.00 Celsius.  Calculate the mass (in grams) of oxygen gas in the cylinder under these conditions (Molar mass of oxygen = 16.00 grams/mol; R = 0.08206 (L x atm)/(mol x K); conversion of Celsius to Kelvin: C + 273.15 = K)  — [HINTS: PV=nRT; Did your units cancel to give the requested unit?]

Which collision factor benefits the most directly from heating a reaction mixture?

Would you expect the following compound to be polar?

50.0 grams of arsenic powder is mixed with 50.0 grams of oxygen gas.  Given the following balanced equation, how many grams of arsenic trioxide is produced?  (Molecular masses: Arsenic = 74.92 g/mol; Oxygen = 16.00; Diarsenic trioxide = 197.84 g/mol) Balanced Equation:  4As(s) + 3O2(g) –> 2As2O3(s) [HINT: How many equations are required to determine the answer?]  

Categorize the following reactions based on their reactants and/or products. Reaction 1: HCl + NaOH → H2O + NaCl Reaction 2: CH4 + 2O2 → 2H2O + CO2 Reaction 3: NaCl(aq) + AgNO3(aq) → AgCl(s) + NaNO3(aq)

In the interest of enhanced buffering capacity, what is the best way to prepare an acidic buffer? [HINT: Read the each question in its entirety]