Question 2.4 please. If 250ml of 1.5M Ba(OH)2 solution mixes with 250ml of 2.0M of HCl solution, calculate the increase in tempe
rature given that the two solutions have the same initial temperatures.
1 answer:
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Answer:
The molarity is 0.359
The molality is 0.354
The mass percent of the solution es 3.45%
Explanation:
Molarity is a unit of concentration that indicates the amount of moles of solute that appear dissolved in each liter of the mixture. It is determined by:
Being:
- K: 39 g/mole
- N: 14 g/mole
- O: 16 g/mole
The molar mass of KNO₃ is:
KNO₃= 39 g/mole + 14 g/mole + 3*16 g/mole= 101 g/mole
You can apply the following rule of three: if 101 grams of KNO₃ are present in 1 mole, 72.5 grams in how many moles are present?
moles of KNO₃= 0.718
So you have:
- moles of KNO₃= 0.718
- volume= 2 L
Applying this quantity in the definition of molarity:
Molarity= 0.359
<u><em>The molarity is 0.359</em></u><u><em></em></u>
Molality is a way of measuring the concentration of solute in solvent and indicates the amount of moles of solute in each kilogram of solvent.
Then the molality is calculated by:
Density is defined as the property that matter, whether solid, liquid or gas, has to compress in a given space. That is, it is the amount of mass per unit volume. So, if the density of 1.05 g / mL for the solution indicates that in 1 mL of solution there are 1.05 grams of solution, in 2000 mL (where 2L = 2000 mL, because 1 L = 1000mL) how much mass is there?
mass= 2100 grams
Since mass solution = mass water + mass KNO₃
then mass water = mass solution - mass KNO₃
Being mass solution 2100 grams and mass KNO₃ 72.5 grams, and replacing you get: mass water= 2100 grams - 72.5 grams
mass water= 2,027.5 grams
Then, being:
- moles of KNO₃= 0.718
- mass of solvent in kilograms= 2.0275 kg (being 2,027.5 grams= 2.0275 kilograms because 1,000 grams= 1 kilogram)
Replacing in the definition of molality:
molality= 0.354
<u><em>The molality is 0.354 </em></u><u><em></em></u>
The mass percent of a solution is the number of grams of solute per 100 grams of solution. Then the mass percent is the mass of the element or solute divided by the mass of the compound or solute and the result of which is multiplied by 100 to give a percentage.
So, in this case:
mass percent= 3.45 % KNO₃ by mass
<u><em>The mass percent of the solution es 3.45%</em></u>