Very easy thermodynamics questions. Please help?

Question

I would really appreciate some help, since I am not getting the first questions of the chapter.

What is the kinetic energy, in J, of (a) an Ar atom moving with a speed of 650 m/s (b) a mole of Ar atoms moving with a speed of 650 m/s? (hint: 1 amu = 1.66 x 10^ -27 kg)

answers are: (a) 1.4 x 10^-20 J (b) 8.4 x 10^3 J

I just dont know how they got that. any help would be appreciated. show all steps please, so that I am to learn. thank you, thank you, thank you so much!!

Answer 1

Well I didn't do the calculations myself, but Kinetic Energy equals: (1/2)(mass)(velocity^2)



So if you plug in the mass (in kilograms) and the velocity, you should get those answers:

(1/2) * (6.631368 × 10^-26 kg) * (650m/s)^2 = 1.4x10^-20



To find answer (b) convert the 1 mole of Argon into its kilogram equivalent and repeat the process:

Find the molar mass of argon (39.95 g/mol). Do the conversions for 1 mol of argon into mass (MAKE SURE ITS KG and not G!!!) and do the same equation



So, summary: (1/2 * m * v^2) is kinetic energy

Answer 2

The enthalpy of fusion is the amount of heat given off when 1 MOLE of acetone melts. So if 63.26 g of acetone give off 6.23 kJ of heat, then how much heat does a mole give off? The molar mass of acetone (CH3COCH3) is 58.0 g / mole. 63.26 g CH3COCH3 x (1 mole CH3COCH3 / 58.0 g CH3COCH3) = 1.09 moles CH3COCH3 6.23 kJ / 1.09 moles CH3COCH3 = 5.72 kJ / mole CH3COCH3

Answer 3

no idea im in 5th grade