Thermodynamics B/C

[UTF-8 U+6211 U+662F]

Okay, not sure if it's my turn or not but:

Why do different solids have different heat capacities?

[CookiePie1]

Okay, not sure if it's my turn or not but:

Why do different solids have different heat capacities?

Answer: The bonds between the atoms of some materials are stronger, thus needing more heat to raise the temperature

[UTF-8 U+6211 U+662F]

Okay, not sure if it's my turn or not but:

Why do different solids have different heat capacities?

Answer: The bonds between the atoms of some materials are stronger, thus needing more heat to raise the temperature

Yep, your turn.

[CookiePie1]

How much heat is required to change ice at -20°C to steam at 120°C? (in Joules)

Constants:
Latent heat of fusion of water = 334,000 J/kg°C
Latent heat of vaporization of water = 2258,000 J/kg°C
Specific heat of ice = 2108 J/kg°C
Specific heat of water = 4186 J/kg°C
Specific heat of steam = 1996 J/kg°C

[JoeyC]

I'm sorry but how much does the ice weigh (or what is its mass)?

[UTF-8 U+6211 U+662F]

How much heat is required to change ice at -20°C to steam at 120°C? (in Joules)

Constants:
Latent heat of fusion of water = 334,000 J/kg°C Units are J/kg
Latent heat of vaporization of water = 2258,000 J/kg°C Units are J/kg
Specific heat of ice = 2108 J/kg°C
Specific heat of water = 4186 J/kg°C
Specific heat of steam = 1996 J/kg°C

Click to Show Answer

20*2108*m+334000*m+100*4186*m+2258000*m+20*1996*m = ~3,090,000 J/kg * m = ~3090 J/g * m

[UTF-8 U+6211 U+662F]

I'll just go... Consider a gas with an rms speed of 500 m/s in a box 1 m x 5 m x 1 m at STP. What is its mass?

[Justin72835]

I'll just go... Consider a gas with an rms speed of 500 m/s in a box 1 m x 5 m x 1 m at STP. What is its mass?

Answer (Click to Show Hidden Text)

[math]v=\sqrt{\frac{3RT}{M}}[/math]

If you plug in 8.314 for R, 273 for T, and 500 for v, you can solve for M (molar mass) which comes out to be 27.23 g/mol. 

Using the ideal gas law, you can solve for the number of moles in the container, which comes out to be 223.2 mol.

From these two values, we can solve for the mass of the gas, which is [b]6.1 kg[/b].

[UTF-8 U+6211 U+662F]

I'll just go... Consider a gas with an rms speed of 500 m/s in a box 1 m x 5 m x 1 m at STP. What is its mass?

Answer (Click to Show Hidden Text)

[math]v=\sqrt{\frac{3RT}{M}}[/math]

If you plug in 8.314 for R, 273 for T, and 500 for v, you can solve for M (molar mass) which comes out to be 27.23 g/mol. 

Using the ideal gas law, you can solve for the number of moles in the container, which comes out to be 223.2 mol.

From these two values, we can solve for the mass of the gas, which is [b]6.1 kg[/b].

Pretty much right, probably off from my answer because of rounding (Click to Show Hidden Text)

[math]M * n = \frac{3RT}{v^2} * \frac{PV}{RT} = \frac{3PV}{v^2} = \frac{3 * 10^5 Pa * 5 m^3}{(500 m/s)^2} = 6 kg[/math]
or
[math]m_0 * N = \frac{3kT}{v^2} * \frac{PV}{kT} = \frac{3PV}{v^2} = 6 kg[/math]

Your turn!

[MattChina]

i guess ill restart this.
What is the point at which solid, liquid and gas phases are in equilibrium called?