# Posts by Amena.S

Total # Posts: 13

1. ### Physics

Over a time interval of 1.98 years, the velocity of a planet orbiting a distant star reverses direction, changing from +21.9 km/s to -17.2 km/s. Find (a) the total change in the planet's velocity (in m/s) and (b) its average acceleration (in m/s2) during this interval. ...
2. ### physics

A 20 kg sphere is at the origin. A 10 kg sphere is at (x,y) = (-30cm,0cm) and a 30 kg sphere is at (0cm,40cm). Calculate the gravitational force on the 10 kg sphere, resulting from the other two spheres. Please help! Thanks
3. ### General Chemistry

Was the concentration of 6.45 x 10^-4 M correct? Just so I know I understand the concept?
4. ### General Chemistry

So I am not sure where things are going wrong?
5. ### General Chemistry

That's the equation I used! I found moles to be 3.22 x 10^-4 mol and concentration to be 6.45 x 10^-4 M. I found the rate to be 8.60 x 10^-7 M/s, but the answer in my textbook is 7.55 x 10^-7 M/s

7. ### General Chemistry

NH4+ + NO2- = N2 + 2H2O A reaction is run, and the liberated N2 gas is collected in a previously evacuated 500 mL container. After the reaction has gone on for 750 seconds, the pressure of N2 in the 500 mL container is 2.77 x 10^-2 atm , and the temperature of the N2 is 250 ...
8. ### General Chemistry

Oh my apologies! It's 38.6 cal/g
9. ### General Chemistry

I'm also wondering why no temperature given. I don't understand why it wouldn't be needed. Thanks
10. ### General Chemistry

Liquid Freon (CCl2F2) is used as a refrigerant. It is circulated inside the cooling coils of older refrigerators or freezers. As it evaporates, it absorbs heat. How much heat can be removed by 2.00 kg of Freon as it evaporates inside the coils of a refrigerator? The heat of ...
11. ### General Chemistry

Thank you very much Arora and DrBob!! You guys were very helpful :)
12. ### General Chemistry

I'm sorry I meant to put a 1.50 L of rubber ballon!
13. ### General Chemistry

A 1.50 rubber balloon balloon is filled with carbon dioxide gas at a temperature of 0.00 degrees celsius and a pressure at 1.00 atm. The density of carbon dioxide under these conditions are 1.98 g/L. At 50.0 degrees celsius, the balloon has a volume of 1.78 L. Calculate the ...