  # A river boat can travel at 20km/hr... Topics: Color, Purple, Sodium, Green, Chemistry / Pages: 2 (370 words) / Published: Oct 16th, 2014

A river boat can travel at 20km per hour in still water. The boat travels 30km upstream against the current then turns around and travels the same distance back with the current. IF the total trip took 7.5 hours, what is the speed of the current? Solve this question algebraically.

Let x = speed of current

Upstream speed=20+x
Downstream speed=20-x
=) 30/20-x + 30/20+x = 7/5
=) (20-x)(20+x) = 400-x^2
=) 30(20-x)+30(20+x)=7.5(400-x^2)
=) 600-30x+600+30x=3000-7.5x^2
=) 7.5x^2 = 3000-1200
=)7.5x^2 = 1800
=)x^2=240
=)x=15.5km/hr

19A Lab Chemistry
1.)When 0.2M is uses, one would use 1/2 number of drops since concentration is twice as much. (higher concentration =>less drops required)Addition of H+ ions will favor the conversion into lighter colored form of the indicator. So basically the more concentrated a substance is, the less of the substance is needed to cause an equilibrium shift.
2.)When HCL is added into the thymol blue, the solution turns blue, so since HCL is an acid, if a base is added into the solution, the equilibrium's reaction would stress and shift, producing the change of color to light yellow. Therefore, when 6.0M NaOH is introduced into the iron(III)thyrocynate, it will turn the solution into a yellow form.
3.)If the hydrated cobalt(II) was to be refrigerated, the prediction of what color it would turn would be that the color will turn lighter (light pink) because the equilibrium is shifted to the left.
4.)Energy would be endothermic for when one added more heat(increase in temp) the solution would change color from light pink to purple(so basically equilibrium must have moved tot he product side(shift right) So temperature should be on the reactant's side(endothermic) in order for the shift to the right to occur.
5.)If one added NCL into the hydrated Coblt(II) ion equilibrium, the concentration of CL ions would increase and Na ions will form and concentration of reactants would increase causing equilibrium to shift to the right