alibaba441

Pv = nRT (http://en.wikipedia.org/wiki/Ideal_gas)

P1V1 = P2V2

P1 = pressure at 9m

V1 = 0.5dm cubed

P2= pressure at 1m

V2 = your answer

what is P1 and P2?

P = Po + density*g*height ( hydrostatic pressure equation https://en.wikipedia.org/wiki/Fluid_statics)

where Po is the atmospheric pressure

P1 = Po + 1000kg/mcubed * 9.81 m/s^2 * 1m = 101,000 + 9810 = 110,000 Pa

P2 = Po + 1000kg/mcubed * 9.81 m/s^2 * 9m = 101,000 +88,290 = 189,000 Pa

ill let you do the rest

if there are a mixture of proteins they will be eluted at different concentrations of NaCl depending on their affinity for the chromatography media. hene you keep all of the wash from the column to analyse later to see which protein was eluted at which concentration.

Fe(s) + 2CuCl2∙2H2O(aq) = 2Cu(s) + FeCl2∙4H2O(aq)

the hydrates cannot exist as

2CuCl2∙2H2O(aq)

if they are dissolved in water. if they are actually aqeous, then the equation becomes:

Fe(s) + 2CuCl2(aq) = 2Cu(s) + FeCl2(aq)

the

2CuCl2∙2H2O can only exist in a crystalline form not when its dissolved in water.

yes the thermal output is indeed ~ 4200J/K for a 1kg bottle.

The heat is going to be emitted in a mixture of conduction (through the skin etc) convection(heat dissipation to the air) and radiation.

Since the temperature of the water bottle never reaches above 80C and drops quite quickly initialy, the radiation aspect is probably small. so the majority of the heat output will be through conduction and convection.

to calculate this we make some assumptions:

the temperature of the water bottle starts at 80C and drops to 20C (room temperature) in the space of 2 hours.

hence we have

Q = M*Cp*dT

where q = TOTAL thermal output (Joules)

M = mass in kg

Cp = heat capacity (J/kg C)

dT = total change in temperature

so we have M = 1kg, Cp = 4200J/Kg C

dT = (80-20) = 60 C

so Q = 4200*60*1 = 252,000 J or 252kJ of thermal energy released over 2 hours

if you want the power you want to know the heat ouput in Joules/s ( Power = energy/time)

P = 252kJ/(2 hours)

P = 252kj/(2*60*60)

P = 35Watts

so a hot water bottle is nowhere near comparable to a 250W incandescent bulb. However, dont forget that not all the energy from a light bubl goes to heat (some will go to light) hence the thermal output of the bulb is slightly lower than its 250W rating.

Its always good to check if your results make sense. the warmth we feel from a water bottle outputting 35 Watts is significant but can we check that it is realistic? Googling caring after a baby squirrel:

http://blogs.fingerlakes1.com/mumsy/raising-orphaned-eastern-grey-squirrels/

reveals that it si suggested they be kept warm by way of a 7 Watt bulb. this is a fifth of the hot water bottle thermal output (approx). this makes sense, a hot water bottle would probably output way too much heat for a small animal to handle so our answer seems to be in the right order of magnitude