Honors Chemistry Questions?

Question

can anyone help me answer these chem problems? (star*means degrees here.)
1. On the planet Xgnu the temperature scale is in *X. On Xgnu, water boils at 140*X and freezes at 14*X. What is the mathematical relationship between *X and *C?
2. A 22.5 gram sample of a metal is heated to 92*C and placed in 50.0 grams of water at 20*C. The metal and water come to thermal equilibrium at 24*C. Calculate the specific heat capacity of the metal.
3. Isopentyl acetate, C7H14O2, is the chemical responsible for the scent of bananas. What is the mass in grams of one molecule of isopentyl acetate?
When you answer, please explain how you got the anwer because I need to show my work on these problems. Thanks for your help!!!

Answer 1

Sorry hun...not doing your homework for you but I can help:
1. Water on Earth boils at 100*C and freezes at 0*c. So now assuming that Xgnu has the same atmospheric conditions as Earth- set the two boiling and freezing temps equal to eachother and reduce. From there plug back in to find what number you need to add/subtract to make both statements true.
2. T2=24*C (same for both substances)
Q(heat added)=C(spec. heat)*M(mass)*(T2-T1). The heat that is removed from the metal is absorbed by the water so set two Q equations equal to eachother (except one is SUBTRACTED because the heat is lost)
(-)Cmetal*Mmetal*(T2-Tmetal)=Cwater*Mwater*(T2-Twater)
OR
Cmetal*Mmetal*(Tmetal-T2)=Cwater*Mwater*(T2-Twater)

Now substitute everything you know into the equation- (go look up the C of water) and solve for Cmetal.
3. Use your periodic table of elements to look up the molecular weight of one g-mole of Carbon, Hydrogen, and Oxygen.
I don't have one on me but to get you on the right track I know Hydrogen is 1.0079 g/g-mole. The subscript number next to each element indicates the number of moles of each element is in one mole of the substance. So multiply the molecular weights of the elements by their subscript and then add together!

Good luck!

Answer 2

hey, i cant help with 2 and 3 since i havent taken chemistry in like 3 years, but question 1 is just a math problem. Im gonna use *D instead of *X just cause its easier using x as a multiplication symbol

ok, so, freezing and boiling temps for Celcius are 0*C and 100*C.

since 0*C multiplied or divided by any number will always give you 0, and the 0*C eqivilant Xgnu temperature is 14*D, then we know that
0*C+14=14*D

But 100*C+14 does not equal 140*D

So now we know that in order to get to 140*D, we're gonna have to multiply 100*C by a number, and then add 14 to get to 140*D

So, working backwards, 140*D-14=126

So now, we have the number that when 14 is added to it, will give you 140. Now we have to get 100 to turn into 126

so, 100*Cx1.26=126

126+14=140*X

so, the formula to convert *C into *D is
*Cx1.26+14=*D

and *D into *C is
(*D-14)/1.26=*C

Its pretty much just like converting Farenheit into celcius, just usin different numbers, good luck with the other two

Answer 3

3. C7H14O2

If you look on the periodic table, C has a mass of 12.01 grams. so 12.01 x 7 = 84.07g
H has a mass of 1 g, so 14 x 1 = 14g
O has a mass of 16 g, so 16 x 2 = 32g
Add them all up: 84.07 + 14 + 32 = 130.07g <--that's your final answer

Answer 4

I don't know the answer to that, but I know that 167 will give you º

as for Q3 add the atomic weights of the molecule and divide by avogadros number to give you the weight. Mighty power has done most of the work for you but that result is for a mole of the substance.