Hey guys, I have three questions from my summer packet that I'm having trouble with at the moment. If anyone is good at chem, help would be appreciated. 1. 125 mL of water is added to to 250 mL of a 1.40 M solution of ammonia. What is the molarity? I'm confused about this one. I can't figure out how to do this. I know it seems simple, but I haven't dealt with problems where water is added to an already existent solution. I'm thinking that I have to figure out the number of moles of ammonia and then divide that by 375 mL (125 mL + 250 mL)/ 2. How many mL of 0.20 M NaOH are required to neutralize 5.4 mL of 1.75 acetic acid? I'm guessing this is a simple M1V1= M2V2 problem. Simply solve for V1. 3. 0.80 g of an unknown monoproctic acid was dissolved in 25.0 mL of water and neutralized with 52.5 mL of 0.125 M KOH. What is the molar mass of the acid? I'm not sure how this problem is supposed to work out. I guess I'd have to figure out how much KOH was used (in moles) and then translate that into a molar mass figure for the acid. The only thing throwing off me off is the 25.0 mL of water. Any and all help is appreciated. Thanks!
Oooft i've not done molarity since school. The first one you just need to add 125mL H2O to the equation. So H2O + NH3 = NH5O (might be the wrong equation, i've not done this in a long time). Obviously you'd need to have the volumes of the liquids in there, I can't remember exactly how to do that then calculate the molarity so I left it out. 2 you know how to do. 3 I have no idea about, i'd have to get my old chem books out again to figure it out.
I'm sure there was an equation to work out number 3, I just can't remember it at the moment. It might be how you said and the 25ml of water could be a red hering (just put there to throw you off), but then again, it's telling you the volume of the solution that was then neutralized by the next part, so i'm not sure.
1. molarity = moles of solute/liter of solution 2. V1 * M1 = V2 * M2 where v1 and v2 are volumes 3. (
Madmax, what would I plug in for the molarity one in number one? I don't understand. Especially cause tiwstedspikes said something else.
I missed the high school chemistry lesson, especially when I was the one the blown up the chemistry labs...lol