Question

The weak acid, HX, is neutralized by sodium hydroxide as shown below: HX(aq) + NaOH(aq) → NaCN(aq) + H2O(1). Suppose you carried out this reaction in a coffee cup calorimeter using 50.0 mL of 0.500 M HX and 0.500 mL of 0.500 M NaOH. If the temperature of the calorimeter increases by 2.08 °C, what is the enthalpy of this neutralization reaction (in kJ/mol)? Assume the density of the solution is 1.00g/mL and that the specific heat is 4.184 J/g °C {Enter your value with the appropriate sign and value, but no units.} RUESTION 2 Colorless gas nitric oxide gas, NO, can react with oxygen to form the brown gas nitrogen dioxide, NO2, as shown below: 2 NO(g) + O2(g) → 2 NO2(g). Suppose you wanted to carry out this reaction in the laboratory. You could filled one gas syringe with 100. mL of nitric oxide and another with 110. mL of oxygen gas. When you connected the syringes and mixed the gases, the reaction mixture changes to a brown color indicating the the reaction had occurred. If the syringes were maintained at constant temperature and pressure, what would be the expected volume of the reaction mixture after the reaction? Hint 1: it is not simply 100+110 mL. Hint 2: nitric oxide is the limiting reagent, which means the end result is a combination of the product gas and the leftover oxygen gas.

Answer 1

1) The enthalpy change is calculated:

ΔH = - m * cp * ΔT H2O / M * V * 1000 = - 50.5 * 4.184 * 2.08 / 0.05 L * 0.5 M * 1000 = - 17.58 kJ / mol

2) 100 mL of NO react with 50 mL of O2, forming 100 mL of NO2.

The final total volume is 160 mL

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