forum.virtualchallengemeets.com

I'm a bit rusty on some of these subjects:

1. How many grams of Cu metal will be plated out of a Cu(NO3)2 solution by passing a current of 3.00 amperes for 11 minutes?


2.
Given:
H3O+ (aq) + NO2- (aq) -> HNO2 (aq) + H20
Kc= 3.78E3 at T=298k
Calculate Kc for the reaction
NO2- (aq) + H2O (l) -> HNO2 (aq) + OH- (aq)



3. What volume of 0.215 molar sodium hydroxide solution would be required to neutralize completely 41.8 mL of a 0.110 molar sulfuric acid solution?

4. Mixing 50 mL of 0.010 M barium hydroxide(aq) and 150mL of 0.010 M nitric acid(aq) will result in a solution with a pH of ____.

5. A 7.78 g sample of gas occupies 1.25 L at STP. What is the molecular weight of the sample?

6. What is the energy of a photon at wavelength = 6580 A
A. 3.0E-15 ergs
B. 6.6E-27 ergs
C. 8.0E-13 ergs
D. 3.0E-12 ergs
E. 8.7E-24 ergs

Well i can answer one
Fits 4 steps
1) Current and time: so multiply the amps they give by the 11 seconds to get coulumbs=33C
2) quantity of charge in Coulombs: C* [unparseable or potentially dangerous latex formula] to get mole of [unparseable or potentially dangerous latex formula]
3)moles of metal: mole [unparseable or potentially dangerous latex formula] *[unparseable or potentially dangerous latex formula]= mol of metal
4)find the grams

Thanks!

Couldn't get this question either...

What is the smallest number of whole logs( with density 660 kg/m^3, diameter 30 cm and length 3 m) that are needed to build a raft that will carry four people who have an average mass of 75 kg SAFELY across a river?