Solve the given problem
3 HCI + AI(OH)3 --> 3 H2O AICI3
1) How many grams og aluminum hydroxide will react 5.3 moles of HCI?
2 NaOH + H2SO4 --> 2 H20 + Na2SO4
2) How many grams of solution of sofium sulfatr will be formed, if you start with 1.25 L of a 4.0 M solution of sodium hydroxide?
Q181304
Solve the given problem
Question 1
How many grams of aluminum hydroxide will react 5.3 moles of HCI?
Solution :
In the given reaction the mol to mol ratio of HCl and Al(OH)3 is 3 :1 .
Using this ratio find the moles of Al(OH)3 that will react with 5.3 moles of HCl .
Next convert 1.77 mol Al(OH)3 to grams by using molar mass of Al(OH)3.
molar mass of Al(OH)3 = 1 * atomic mass of Al + 3 * atomic mass of O + 3 * atomic mass of H.
= 1 * 26.982 g/mol + 3 * 15.999 g/mol + 3 * 1.00794 g/mol
= 78.0028 g/mol
Using molar mass 78.0028 g/mol convert 1.77 mol Al(OH)3 to grams.
"= 138.06\\ grams \\ of \\ Al(OH)_3"
In question we are given 5.3 mole HCl in 2 significant figure, so our final answer must also be in
2 significant figure.
-------------------------------------------x--------------------------------------------------x-------------------------------------------x----------------------
Question 2
How many grams of solution of sodium sulfate will be formed, if you start with 1.25 L of a 4.0 M solution of sodium hydroxide?
Solution :
Step 1 : To find the moles of NaOH present in 1.25 L of 4.0 M solution.
Let us first find the moles of NaOH present in 1.25 L of 4.0 M solution of sodium hydroxide.
Plug volume = 1.25 L and molarity = 4.0 M in the molarity formula and find the
moles of NaOH.
"4.0M = \\frac{moles \\ of \\ NaOH }{1.25 \\ L }"
Arranging the equation for ' moles of NaOH' , we have
Step 2 : To find the moles of Na2SO4 that is formed from 5.0 moles of NaOH.
The reaction of NaOH and H2SO4 is
The mol to mol ratio of NaOH and Na2SO4 in this reaction is 2 mol NaOH : 1 mol Na2SO4.
Using this ratio find the moles of Na2SO4 that will be formed from 5.0 moles of NaOH.
"= 2.5 \\ mol \\ Na_2SO_4"
Step 3 : Convert 2.5 mol Na2SO4 to grams by using molar mass of Na2SO4.
molar mass of Na2SO4 = 2 * atomic mass of Na + 1 * atomic mass of S + 4 * atomic mass of O
= 2 * 22.99 g/mol + 1 * 32.065 g/mol + 4 * 15.999 g/mol
= 142.041 g/mol
Using molar mass 142.041 g/mol convert 2.5 moles of Na2SO4 to grams.
"= 355.1 \\ grams \\ of \\ Na_2SO_4"
In correct significant figure the answer will be 360 grams of Na2SO4.
The molarity given in the question is in 2 significant figure ( which is least)
So our final answer must also be in 2 significant figure.
Comments
Leave a comment