What is the molarity of a solution containing 18.2 g of KCl in 215 mL of KCl solution?
1 answer:
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Answer:
The molarity (M) of the following solutions are :
A. M = 0.88 M
B. M = 0.76 M
Explanation:
A. Molarity (M) of 19.2 g of Al(OH)3 dissolved in water to make 280 mL of solution.
Molar mass of Al(OH)3 = Mass of Al + 3(mass of O + mass of H)
= 27 + 3(16 + 1)
= 27 + 3(17) = 27 + 51
= 78 g/mole
= 78 g/mole
Given mass= 19.2 g/mole
Moles = 0.246
Volume = 280 mL = 0.280 L
Molarity = 0.879 M
Molarity = 0.88 M
B .The molarity (M) of a 2.6 L solution made with 235.9 g of KBr
Molar mass of KBr = 119 g/mole
Given mass = 235.9 g
Moles = 1.98
Volume = 2.6 L
Molarity = 0.762 M
Molarity = 0.76 M
Answer : The correct option is, (B) 6 mole
Explanation :
Given moles of = 6 moles
Given moles of = 6 moles
First we have to calculate the limiting and excess reagent.
The balanced chemical reaction is,
From the given balanced reaction, we conclude that
As, 1 moles of react with 2 moles of
So, 6 moles of react with
moles of
From this we conclude that, is an excess reagent and
is a limiting reagent because the given moles are less than the required moles and it limits the formation of product.
Thus, the number of moles of NaOH used up in the reaction = Required moles of NaOH - Given moles of NaOH
The number of moles of NaOH used up in the reaction = 12 - 6 = 6 moles
Therefore, the number of moles of NaOH used up in the reaction will be, 60 moles