Answer:
The Ka value used for the buffer system is :- Ka2 = pKa2 = 7.2
pH = 7.1
Explanation:
The buffer system given in the question is :-
and
The reaction taking place is:-
The Ka value used for the buffer system is :- Ka2 = pKa2 = 7.2
The pH can be calculated as:-
pH = 7.2 + log 0.40/0.50 = 7.1
By increasing Atomic number
The correct answer is D) ) It uses the mass and specific heat of water along with a thermometer to measure the gain or loss of energy when a substance is added.
The statement that describes how a basic coffee cup calorimeter works is: "It uses the mass and specific heat of water along with a thermometer to measure the gain or loss of energy when a substance is added."
To measure the heat flow during a chemical reaction we use the device called Calorimeter. This device has a combustion chamber and above it, a metal container of water. With the use of a thermometer, we can measure the change in temperature. The combustion chamber releases the heat. This increases the temperature of the water.
The other options of the question were A) It measures the mass of a substance given the specific heat and temperature of water in a cup of known size. B) It measures the density of a substance given the mass, specific heat, and temperature of water in a cup of known size. C) It uses the mass and specific heat of water along with a pressure gauge to measure the gain or loss of energy when a substance is added.
Answer:
The correct answer is 146 g/mol
Explanation:
<em>Freezing point depression</em> is a colligative property related to the number of particles of solute dissolved in a solvent. It is given by:
ΔTf = Kf x m
Where ΔTf is the freezing point depression (in ºC), Kf is a constant for the solvent and m is the molality of solution. From the problem, we know the following data:
ΔTf = 1.02ºC
Kf = 5.12ºC/m
From this, we can calculate the molality:
m = ΔTf/Kf = 1.02ºC/(5.12ºC/m)= 0.199 m
The molality of a solution is defined as the moles of solute per kg of solvent. Thus, we can multiply the molality by the mass of solvent in kg (250 g= 0.25 kg) to obtain the moles of solute:
0.199 mol/kg benzene x 0.25 kg = 0.0498 moles solute
There are 0.0498 moles of solute dissolved in the solution. To calculate the molar mass of the solute, we divide the mass (7.27 g) into the moles:
molar mass = mass/mol = 7.27 g/(0.0498 mol) = 145.9 g/mol ≅ 146 g/mol
<em>Therefore, the molar mass of the compound is 146 g/mol </em>