Homework answers / question archive / Question 110 pts In the figure below, what is the pressure of the gas in the flask (in atm) if the barometer reads 765

Question 110 pts In the figure below, what is the pressure of the gas in the flask (in atm) if the barometer reads 765

Chemistry

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Question 110 pts

In the figure below, what is the pressure of the gas in the flask (in atm) if the barometer reads 765.4 torr?   Hint:  What type of manometer is this?

 

Question 210 pts

A child holds a helium-filled balloon with a volume of 350. mL at sea level (1.00 atmosphere pressure) at 25.0 °C.  He releases the balloon.  What is the final volume after the balloon has travelled to an altitude of 5 km where the temperature is -19.1 °C and the pressure is 0.530 atm? (Show work)

 

Question 310 pts

Aluminum reacts with excess hydrochloric acid to producing 51.0 mL of hydrogen gas over water at 25°C and 751 mmHg. Aluminum chloride is the other product.  The vapor pressure of water at 25°C is 24.3 mm Hg. How many grams of aluminum reacted?  (Hint:  Write the balanced equation first). (Show work)

 

Question 410 pts

7. Classify the following processes as exothermic or endothermic.  Answer with exothermic or endothermic (no capitals).

 

1. a) Sublimation (going from solid to gas) of dry ice (CO₂) is 
2. b) Formation of ice from liquid water is 
3. c) Baking a cake is 
4. d) A flask containing a reaction mixture feels cold to the touch from a bare hand (the system is the reaction mixture) is 
5. e) A candle flame is 

 

Question 510 pts

Calculate the pressure of 3.00 Liters of a gas at 25.0 °C if it has a volume of 5.00 Liters at STP. (Show work)

 

Question 610 pts

The combustion of isoctane reaction produces -5099.5 kJ of heat per mole of C₈H₁₈ (g) consumed, under standard conditions.  The enthalpy of formation (DH_f) for CO₂(g) and H₂O (g) are -393.5 kJ/mol and -241.8 kJ/mol, respectively.  Find the standard enthalpy of formation (DH_f) of this isomer of C₈H₁₈ (g)? (Show work)

 

C₈H₁₈ (g) + O₂(g) -> 8CO₂(g) + 9H₂O(g)  DH_rxn = -5099.5 kJ

 

Question 710 pts

What is ΔH ( in kJ/mol) for the following reaction? (Show work)

 

CS₂(l) + 3 O₂(g) → CO₂(g) + 2 SO₂(g)

 

Given:

C(s) + O₂(g) → CO₂(g); ΔH_f = -393.5 kJ/mol

S(s) + O₂(g) → SO₂(g); ΔH_f = -296.8 kJ/mol

C(s) + 2 S(s) → CS₂(l); ΔH_f = 87.9 kJ/mol

Group of answer choices

-1075.0

-602.4

-778.2

-899.2

None of the above

 

Question 810 pts

After heating 30 grams of an unknown metal to 100.0 °C, it is added to a calorimeter containing 20 mL of water at 25.0 °C.  The final temperature of the calorimeter is 28.3 °C.  Identify the the metal?  (Show work)

c (specific heat capacity) of Fe = 0.44 J/g °C; Al = 0.90 J/g °C, Au = 0.13 J/g °C; Cu = 0.38 J/ g °C H₂O = 4.184 J/g °C

Density of H₂O = 1.0 g/mL

 

Group of answer choices

Au

Fe

Cu

Al

 

Question 98 pts

Find q (heat) when 1.22 mol of water is heated from 25.0°C to 100. °C.  (The specific heat capacity for liquid water is 4.184 J/ g·K). (Show work)

 

Question 108 pts

a) Why do heat (q) and work (w) have positive values when they enter a system but negative values when they leave the system?   b) Why does sweating help cool you down after exercising? Explain.

Question 111 pts

If you increase the number of moles of a system at constant temperature and constant pressure you will also increase the volume.

Group of answer choices

True

False

Question 121 pts

Volume of a gas is directly proportional to the mass of the gas, not the number of moles

Group of answer choices

True

False

Question 131 pts

A real gas tends to behave like an ideal gas at high temperature and low pressure conditions.

Group of answer choices

True

False

Question 141 pts

At constant temperature, if the volume of the container is increased then the pressure is increased also.

Group of answer choices

True

False

Question 152 pts

EXTRA CREDIT

Helium will behave more like an ideal gas than ammonia because it is smaller and has weaker intermolecular forces.

 

Group of answer choices

True

False

Question 166 pts

EXTRA CREDIT

Ice melts to liquid water at 0.0°C and it absorbs 0.334kJ of heat per
gram. Suppose the heat needed to melt 50.0 g of ice is absorbed from the water
contained in a glass. The mass of this water is 0.300 kg with a temperature of
24.0°C. What is the final temperature of the water? [Note that you will have 50.0
g of water at 0°C from the ice.] (Show work)