I have a quiz tomorrow on molarity and i still don't understand some homework questions.
Please help me solve the following questions.
How many mL of a .5M K2 Cr2 O7 must be evaporated to dryness in order to end up with a 2.948g of solid K2 Cr2 O7.
How many grams of sodium chloride are present in 45mL of .125M NaCl?
How many liters of .5M C6 H12 O6, solution will contain exactly 100g glucose?
What is the molarity of a solution made by dissolving 10.6g of NaCO3 in 400mL of water?
A person mixes 100mL of a .5 M NaOH solution with 150mL of a .3M NaOH solution. What is the molarity of the resulting NaOH solution?
2006-11-16 11:20:05 · 6 answers · asked by > 2 in Science & Mathematics ➔ Chemistry
Start with 2.948g K2Cr2O7. End with how many mL. K=39, Cr=52, O=16, K2Cr2O7=294. Multiply by 1molK2Cr2O7/294gK2Cr2O7. The gK2Cr2O7 cancel, leaving molK2Cr2O7. Multiply by 1000mLK2Cr2O7/0.5molK2Cr2O7. This comes from 0.5M, which means 0.5 mol in 1000mL. The molK2Cr2O7 cancel, leaving mL solution to be evaporated.
Start with 45mL NaCl, end with gNaCl. Na=23, Cl=35.5, NaCl=58.5. Multiply by 0.125molNaCl/1000mLNaCl. This comes from 0.125M. The mLNaCl cancel, leaving molNaCl. Multiply by 58.5gNaCl/1molNaCl. The molNaCl cancel, leaving the gNaCl that is the answer.
Start with 100g glucose, G. End with L of G. C=12, H=1, O=16, C6H12O6=180. Multiply by 1molG/180gG. The gG cancel, leaving molG. Multiply by 1L G/0.5molG. This comes from 0.5M G. molG cancel, leaving L of G. Which is the answer.
2006-11-16 11:55:47 · answer #1 · answered by steve_geo1 7 · 0⤊ 0⤋
Molarity is concentration (n/v=C) first locate the moles (n) by using taking your mass divided over your molar mass (you will locate the molar hundreds of Ag etc. on the periodic table for sure) then you take that style and placed it divided over your 0.335L of answer (as a results of fact it must be in Liters, so the final instruments are mol/L) happy Chemistry-ing!
2016-12-30 13:43:34 · answer #2 · answered by ? 3 · 0⤊ 0⤋
All of your questions are simple molarity and titration stochiometry. You must first set your equation and balance it then walk your self through the steps of stochiometry. If your are given grams then get your molar mass of the compound and set it equal to moles. then find find how many moles of that solution are being used in your equation and react with how many moles of the other solution and set it equal to L as in a molar solution and that will given you the amount of liters used and simply multiply that by 1000 to find your ml.
2006-11-16 11:49:13 · answer #3 · answered by gsalinas_44 1 · 0⤊ 0⤋
It would help if you would post the molecular weights of all these compounds. Otherwise, answering this is just too much work.
2006-11-16 12:11:14 · answer #4 · answered by Luha 3 · 0⤊ 0⤋
To those questions as asked, I don't know. Try again with real questions.
2006-11-16 11:36:40 · answer #5 · answered by Anonymous · 0⤊ 0⤋
M=mole/L
2006-11-16 11:29:09 · answer #6 · answered by 7 · 0⤊ 0⤋