Hello.
For my chemistry of solutions class, we had a titration lab where we titrated NaOH into an HCl + H2O mix. This was a preparatory titration for the next one consisting of the hydrolysis of ethyl acetate into acetic acid with H+ ions as a catalyst (in our case the HCl).
So now, after we did 4 stock HCl titrations which are the practice ones, we're asked those 2 questions:
Mass of HCl in 5.00 mL HCl solution
Mass of 5.00 mL HCl solution (d=1.05g/mL)
Now I put the same answer in both as 5mL * 1.05 g/mL = 5.25g.
So my question is, what exactly is the difference between those 2 questions, are they asking for the same thing?
Also, further down they ask to find the Mass of H2O in 5mL HCl solution and the moles of H2O. Is this going to be calculated using the water density?
Thank you for your time.
So I was thinking that when we use the NaOH, because of the stoichiometry of it's reaction with HCl, would the mass used of NaOH be the same for HCl, when it reaches equilibrium, well the neutral pH? Or am I completely off
Those are two different questions.
mass HCl in 5.00 mL = mols HCl in 5.00 mL x molar mass HCl
mass 5.00 mL soln = 5.00 x 1.05 g/mL = ?
Because of the stoichiometry of the titration of NaOH + HCl, the MOLES are equal at the equivalence point but not the grams. 1mol HCl = 1 mol NaOH or 36.5 g HCl and 40 g NaOH. So mols are equal but not grams.
Amazing, thank you DrBob!
Hello!
Let's break down the questions one by one and understand the difference between them:
1. Mass of HCl in 5.00 mL HCl solution: This question is asking for the mass of only the HCl present in the solution. It wants you to determine the amount of HCl, in grams, in a 5.00 mL solution.
On the other hand, the second question is:
2. Mass of 5.00 mL HCl solution (d=1.05 g/mL): This question is asking for the total mass of the entire HCl solution. It wants you to calculate the mass of the whole 5.00 mL solution, which includes both the HCl and the solvent (water). The density of the solution given is 1.05 g/mL.
So, these two questions are different since the first one asks for the mass of only the HCl, while the second one asks for the mass of the entire solution.
Now, moving on to your question about calculating the mass of H2O in the HCl solution:
Yes, you will need to use the density of water to calculate the mass of water in the solution. To do this, you can use the following equation:
Mass of water (in grams) = Volume of water (in mL) × Density of water (in g/mL)
In this case, the volume of water is 5.00 mL, and you can assume the density of water as 1.00 g/mL. So, you can now calculate the mass of water in the 5.00 mL HCl solution.
Finally, to find the moles of H2O, you will need to use the molar mass of water, which is approximately 18.015 g/mol. You can calculate the moles of water by dividing its mass (in grams) by the molar mass.
I hope this helps! Let me know if you have any further questions.