The equation we want to use = q = mc (delta t) where q is heat in joules, m is mass in kilograms, c is the heat capacity (water's heat capacity in all 3 phases are pretty common and easy to memorize) and delta t is the change in the temperature. q will equal 390 because since we need kJ we must convert the 3.9x10^5 that we have by moving the decimal 3 places. so 390 = (.9)(2.03) delta t .... solve for delta t and you should get 213.5 which is the change in temperature but since they have 2 sig digs in all their numbers I would go with 210... so .5 + 210 is 205. And for part B, it is basically asking if we want the same delta t, but we multipled q by 3.6 what would the mass have to change to (since we know the heat capacity is definitely not changing ) ... so if we multiply the q by 3.6 the m must be multiplied by the same number
Apr 15th, 2015
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