Stoichiometry; calculation headaches

In summary, a 2.5g sample of impure CaCO3 was dissolved in 25.0cm^3 of 2.00 mol dm^-3 HCL to create Solution X. 15.0cm^3 of Solution X required 20.0cm^3 of 0.0500 mol dm^-3 NaOH for neutralization. To calculate the number of moles of HCL that reacted with the CaCO3, the initial moles of HCL and the moles of NaOH reacted with the excess HCL were calculated. The difference between the initial moles and excess moles was then used to determine the amount of excess HCL present.
  • #1
thepoll
2
0
Hi, I've been trying and trying but I can't seem to solve this. Hopefully, there's someone here kind enough to help me through :X

2.5g of impure CaCO3 was dissolved in 25.0cm^3 of 2.00 mol dm^-3 HCL in a 100cm^3 volumetric flask and made up to the mark with distilled water. This solution is labelled as Solution X. 15.0cm^3 of this mixture required 20.0cm^3 of 0.0500 mol dm^-3 NaOH for neutralization.



Calculate the number of moles of HCL that has reacted with 2.5g of CaCO3.



1. I calculated the mole of HCL in 25.00cm^3 of 2.00 mol dm^-3 solution and also the number of moles of NaOH required to be titrated with 25cm^3 of the mixture of X.
2. I then tried calculating the concentration of Solution X that contains excess HCL. However, I got stuck there. If anyone could just hint me the next step, I would greatly appreciate it! thanks:)
 
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  • #2
How many moles of HCl initially?

How many moles of NaOH reacted with the excess HCl?

How much of the excess HCl was present?

Then it is just initial minus excess.
 
  • #3
thanks! I managed to solve it. a lil tricky though (:
 

FAQ: Stoichiometry; calculation headaches

What is stoichiometry?

Stoichiometry is the branch of chemistry that deals with the quantitative relationships between reactants and products in a chemical reaction. It involves using mathematical calculations to determine the amount of products formed from a given amount of reactants.

Why is stoichiometry important?

Stoichiometry is important because it allows us to accurately predict the amount of products that will be formed in a chemical reaction. This information is crucial in many practical applications, such as determining the amount of reactants needed to produce a certain amount of product.

What are the units used in stoichiometry?

The units used in stoichiometry are typically moles (mol) for the amount of substances, and grams (g) for the mass of substances. These units are used in calculations to determine the amount of products formed, based on the given amount of reactants.

What are the common calculation headaches in stoichiometry?

Some common calculation headaches in stoichiometry include determining the limiting reactant, dealing with excess reactants, and converting between units. These can be tricky to solve and require careful attention to ensure accurate calculations.

How can one improve their stoichiometry skills?

The best way to improve stoichiometry skills is through practice and understanding the underlying concepts. It is also helpful to carefully read and understand the problem, and to double check all calculations to avoid errors. Additionally, seeking help from a tutor or teacher can also improve stoichiometry skills.

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