1. You have been given a sample of unknown molarity. Calculate the molarity of a solution which has been prepared by dissolving 8.75 moles of sodium chloride in enough water to produce a solution of 6.22l.
2. You have a sample which consists of 428g sodium hydroxide (NaOH) dissolved in enough water to make a final solution of 6.4l. What is the molarity?
3. You have been given a sample of 4.85 moles of glucose (C6H12O6) and you want to make a 0.75M solution with it. What will be the final volume of solution?
4. 37.0cm³ of a sodium hydroxide (NaOH) solution was pipetted into a conical flask and titrated with a standard solution of 0.45 mol dm-3 (0.3M) hydrochloric acid according to the following equation:
NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l)
A universal indicator solution was used for the titration and it was found that 22.0 cm3 of the acid (HCl) was required to neutralise the alkali (NaOH). Calculate the molarity of the sodium hydroxide and its concentration in g/dm3.
1. To calculate the molarity of a solution, you need to divide the moles of solute by the volume of the solution in liters.
In this case, you have been given 8.75 moles of sodium chloride (NaCl) and a solution volume of 6.22 liters. Therefore:
Molarity = Moles of Solute / Volume of Solution
Molarity = 8.75 moles / 6.22 L
Molarity = 1.407 M
So, the molarity of the solution is 1.407 M.
2. To calculate the molarity of a solution, you need to divide the moles of solute by the volume of the solution in liters.
In this case, you have a sample of 428g of sodium hydroxide (NaOH) and a solution volume of 6.4 liters. First, you need to convert the mass of NaOH to moles using its molar mass.
Molar mass of NaOH = 22.99 g/mol (atomic mass of Na) + 15.999 g/mol (atomic mass of O) + 1.007 g/mol (atomic mass of H)
Molar mass of NaOH = 40.006 g/mol
Now, calculate the moles of NaOH:
Moles of NaOH = Mass of NaOH / Molar mass of NaOH
Moles of NaOH = 428 g / 40.006 g/mol
Moles of NaOH = 10.696 mol
Finally, calculate the molarity of the solution:
Molarity = Moles of Solute / Volume of Solution
Molarity = 10.696 mol / 6.4 L
Molarity = 1.67 M
So, the molarity of the solution is 1.67 M.
3. To determine the final volume of a solution, you can use the formula for molarity:
Molarity = Moles of Solute / Volume of Solution
In this case, you have been given 4.85 moles of glucose (C6H12O6) and you want to make a 0.75 M solution. Rearrange the formula to solve for the volume:
Volume of Solution = Moles of Solute / Molarity
Volume of Solution = 4.85 mol / 0.75 M
Volume of Solution = 6.47 L
So, the final volume of the solution will be 6.47 liters.
4. To calculate the molarity of the sodium hydroxide (NaOH) solution and its concentration in g/dm³, you need to use the equation and the volume of the hydrochloric acid (HCl) required for neutralization.
From the equation: 1 mole of NaOH reacts with 1 mole of HCl. So the moles of NaOH can be calculated using the volume and molarity of HCl.
Moles of HCl = Volume of HCl (L) × Molarity of HCl (mol/L)
Moles of HCl = 0.022 L × 0.45 mol/L
Moles of HCl = 0.0099 mol
Since the mole ratio between NaOH and HCl is 1:1, the moles of NaOH are also 0.0099 mol.
Now, we can calculate the molarity of NaOH:
Molarity of NaOH = Moles of NaOH / Volume of NaOH (L)
Molarity of NaOH = 0.0099 mol / 0.037 L
Molarity of NaOH = 0.267 M
To calculate the concentration in g/dm³, we need to convert the molarity to mass and volume:
Concentration in g/dm³ = Molarity of NaOH (mol/L) × Molar mass of NaOH (g/mol) × 1000 (to convert dm³ to cm³)
Concentration in g/dm³ = 0.267 mol/L × 40.006 g/mol × 1000
Concentration in g/dm³ = 10670.42 g/dm³
So, the molarity of the sodium hydroxide solution is 0.267 M, and its concentration is 10670.42 g/dm³.