A quantity of 16.13 mL of a KOH solution is needed to neutralize 0.4883 g of KHP. What is the concentration (in molarity) of the KOH solution?
I don't even know where to begin with the first one.
Calculate the amount of heat liberated (in kJ) from 375 g of mercury when it cools from 71.3°C to 18.0°C.
Is heat liberate a term for something else?
Convert 0.4883 g KHP to moles; moles = grams/molar mass.
Since the neutralization of KOH with KHP is 1:1 in the balanced, then moles KOH used = moles KHP.
moles KOH = M x L.
You know moles, you know L, calculate M.
For #2, yes, liberating heat means the reaction is exothermic (and delta H for the reaction is negative).
For the first question, you can find the concentration of the KOH solution by using the equation:
Molarity (M) = moles of solute / volume of solution (in liters)
To find the moles of solute (KOH) in this case, you need to start by determining the moles of KHP (potassium hydrogen phthalate), which is neutralized by the KOH.
1. Convert the given mass of KHP (0.4883 g) to moles by dividing it by the molar mass of KHP. The molar mass of KHP can be found by adding the atomic masses of its constituent elements (potassium, hydrogen, carbon, and oxygen) from the periodic table.
2. Once you have the moles of KHP, you can use the stoichiometry of the balanced chemical equation between KHP and KOH to determine the moles of KOH. The balanced equation should be provided or can be looked up.
3. The volume of solution is given as 16.13 mL. Convert this to liters by dividing by 1000.
4. Divide the moles of KOH by the volume of solution in liters to find the concentration (molarity) of the KOH solution.
For the second question, "heat liberated" refers to the amount of heat energy that is released during a process. To calculate the heat liberated when a substance cools, you can use the equation:
q = m * C * ΔT
where:
q is the heat liberated (in joules or calories),
m is the mass of the substance (in grams),
C is the specific heat capacity of the substance (in J/g°C or cal/g°C), and
ΔT is the change in temperature (in °C).
Note that 1 cal = 4.184 J.
To solve the problem, you need to know the specific heat capacity of mercury, which can be found in reference books or online databases. Once you have that value, substitute the given values (mass, initial temperature, and final temperature) into the equation to find the amount of heat liberated.