The concentration of a certain sodium hydroxide solution was determined by using the solution to titrate a sample of potassium h
ydrogen phthalate (abbreviated as KHP). KHP is an acid with one acidic hydrogen and a molar mass of 204.22 g/mol. In the titration, 23.46 mL of the sodium hydroxide solution was required to react with 0.1082 g KHP. Calculate the molarity of the sodium hydroxide.
The molarity is the number of mol solute divided by the volume of solution in liters. Since we are told there is only one acidic hydrogen in KHP the reaction is a 1 to 1 with sodium hydroxide, We then calculate the moles of sodium hydroxide required to react with the moles of KHP and proceed to calculate the molarity of the NaOH solution:
mol KHP: 0.1082 g x 1 mol/204.22 g = 0.00053 mol KHP
Taking into account the definition of calorimetry, 0.0185 moles of water are required.
<h3>Calorimetry</h3>
Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.
Sensible heat is defined as the amount of heat that a body absorbs or releases without any changes in its physical state (phase change).
So, the equation that allows to calculate heat exchanges is:
Q = c× m× ΔT
where Q is the heat exchanged by a body of mass m, made up of a specific heat substance c and where ΔT is the temperature variation.
<h3>Mass of water required</h3>
In this case, you know:
Heat= 92.048 kJ
Mass of water = ?
Initial temperature of water= 34 ºC
Final temperature of water= 100 ºC
Specific heat of water = 4.186
Replacing in the expression to calculate heat exchanges:
92.048 kJ = 4.186 × m× (100 °C -34 °C)
92.048 kJ = 4.186 × m× 66 °C
m= 92.048 kJ ÷ (4.186 × 66 °C)
<u><em>m= 0.333 grams</em></u>
<h3>Moles of water required</h3>
Being the molar mass of water 18 , that is, the amount of mass that a substance contains in one mole, the moles of water required can be calculated as: