1. What does 'the time taken to reach completion decreases if 20cm^3 of hcl containing 4mol/dm^3' means? How to work out to find the concentration?
2(a)What does concentrated hcl means?
(b)What does dilute hcl means?
Which will react faster or slower / a or b?
Thanks sooooo much !!
You need to clarify this post if you expect an answer. I have no idea what you're talking about.
1. The statement "the time taken to reach completion decreases if 20cm^3 of HCl containing 4mol/dm^3" is referring to a chemical reaction with HCl (hydrochloric acid) as one of the reactants. It means that if you add 20cm^3 of HCl solution with a concentration of 4 mol/dm^3, the reaction will reach completion faster than if you were to add a solution with a lower concentration.
To find the concentration, you can use the formula:
Concentration (mol/dm^3) = Amount of substance (mol) / Volume of solution (dm^3)
In this case, you are given that the volume of the HCl solution is 20cm^3 (which is equivalent to 0.02dm^3) and that the HCl solution contains 4 mol/dm^3. You want to find the amount of substance (mol), so the formula can be rearranged as:
Amount of substance (mol) = Concentration (mol/dm^3) * Volume of solution (dm^3)
So, you can find the amount of substance in this case by multiplying 4 mol/dm^3 by 0.02dm^3:
Amount of substance (mol) = 4 mol/dm^3 * 0.02 dm^3 = 0.08 mol
Therefore, the concentration of the HCl solution is 4 mol/dm^3, and there is 0.08 mol of HCl in the 20cm^3 solution.
2(a) Concentrated HCl refers to a solution of hydrochloric acid that has a high concentration of HCl molecules dissolved in it. This means that there is a large amount of HCl present relative to the amount of solvent (usually water) in the solution.
2(b) Dilute HCl refers to a solution of hydrochloric acid that has a low concentration of HCl molecules dissolved in it. This means that there is a small amount of HCl present relative to the amount of solvent (usually water) in the solution.
In terms of reaction rate, concentrated HCl will typically react faster than dilute HCl. This is because there are more HCl molecules available to react in a given volume of solution, leading to a higher frequency of successful collisions and therefore a faster reaction rate.