Question

The addition of 3.15 g of ba(oh)2 8h2o to a solution of 1.52 g of nh4scn in 100 g of water in a calorimeter caused the temperature to fall by 3.1°c. assuming the specific heat of the solution and products is 4.20 j/g °c, calculate the approximate amount of heat absorbed by the reaction, which can be represented by the following equation?

a) Ba(OH)2·8H2O + NH4SCN → Ba(SCN)2 + 2H2O
b) Ba(OH)2·8H2O + 2NH4SCN → Ba(SCN)2 + 10H2O
c) Ba(OH)2·8H2O + NH4SCN → BaO + 2H2O + NH3 + CO2
d) Ba(OH)2·8H2O + NH4SCN → BaCO3 + 2NH3 + 10H2O

Answer 1

The heat absorbed by the reaction of Ba(OH)2·8H2O with NH4SCN, with a resultant temperature decrease of 3.1°C, is approximately 1358.63 joules, determined using the specific heat capacity and total mass of the reactants and the calorimeter water.

Step-by-step explanation:

You're asking about the calculation of the heat absorbed by the reaction in which Ba(OH)2·8H2O is mixed with NH4SCN. The reaction absorbs heat, as indicated by the decrease in temperature in the calorimeter.

To calculate the heat absorbed (q), we use the formula: q = m × Cs × ΔT, where m is the mass of the solutions and products, Cs is the specific heat capacity, and ΔT is the temperature change. In this reaction, the combined mass is the mass of the added barium hydroxide octahydrate, ammonium thiocyanate, and the water in the calorimeter. The specific heat capacity is given as 4.20 J/g°C, and the temperature change is -3.1°C.

To find the heat absorbed:

• Calculate the total mass (m): mass of Ba(OH)2·8H2O + mass of NH4SCN + mass of water = 3.15 g + 1.52 g + 100 g = 104.67 g.
• Use the above mass in the formula with the given Cs and ΔT values:
• q = 104.67 g × 4.20 J/g°C × (-3.1°C) = -1358.63 J

The negative value indicates that the reaction is endothermic and absorbs approximately 1358.63 joules of heat from the surroundings.