Ch. 4 Chem 101 Problems

What is the specific heat capacity of water?

1.00 Cal/ (g*°C)

How many kilocalories are in 4222 J?

1.01 kcal 1 kcal= 4184 J *CONVERT JOULES TO KCAL 4222 J * (1 kcal)/(4184 J) =4222/4184 = 1.009 *ROUND =1.01 kcal

If a person practicing yoga for one hour burns 325 kcal how many joules of energy have they burned?

1.36 x 10^6 J 1 kcal = 4184 J 325 kcal * (4184 J)/(1 kcal) = 325*4184 = 1,359,800 *ROUND ANSWER TO CORRECT SIG FIGS =1,360,000 -> 1.36 x 10^6 J

If 701 J of heat is available, what is the mass in grams of iron (specific heat=0.450 J/g*°C) that can be heated from 22.5 °C to 120.0°C?

15.98 g Change in Temp= 120 °C- 22.5 °C = 97.5 °C 701 J= m(0.450 J)* 97.5 °C *DIVIDE BOTH SIDES BY 97.5 7.19= m(0.450 J) *DIVIDE BOTH SIDES BY 0.450 m= 15.98

What is the final temperature in °C of 820.1 g of water (specific heat= 4.184 J/g*°C) at 24.20°C that absorbed 950.0 J of heat?

24.477°C Change in T= (950.0 J) / (820.1 g * 4.184 J/g*°C) *CANCEL OUT SIGNS Change in T= (950.0 J)/(3,431.2984) -> 0.2769 *ADD TO ORIGINAL TEMP (24.30°C) Change in T= 24.4769 °C *ROUND = 24.477 °C

How many Joules are there in 65.5 kcal? (1 cal= 4.184 J)

274,052 J 65.5 kcal * (4184 J/1 kcal) = 274,052 J

How many Calories are found in a frozen pizza that has 17 g of fat, 38 g of carbohydrates, and 13 g of protein?

360 Calories

The predominant intermolecular force between molecules of I2 is __?

Dispersion forces

What represents the IMF present in CO2?

Dispersion forces

List the 3 types of IMF from weakest to strongest

London Dispersion, Dipole-Dipole, and Hydrogen Bonding

How to determine which IMF a substance will have

Nonpolar compound: London Dispersion Polar compound: London Dispersion and Dipole-Dipole Compound with H-F, H-O, H-N: London Dispersion, Dipole-Dipole, and Hydrogen Bonding

How many Cal/g are in each marco?

Protein- 4 Cal/g Carbohydrate- 4 Cal/g Fat- 9 Cal/g

How can you determine which substance has the highest boiling point?

The substance with the strongest IMF will require a larger amount of energy to break the connection between the molecules, therefore it will have a higher boiling point

How can you determine which substance has the lowest boiling point?

The substance with the weakest IMF (Intermolecular Forces) - Boiling points of Alkanes (Hydrocarbons) increase as the # of Carbon atoms increases

Which of the following has the lowest boiling point? a.) C5H12 b.) C7H16 c.) C9H20 d.) C11H24 e.) C13H28

a.) C5H12

Which of the following compounds can form IMF hydrogen bonds? a.) H20 b.) HCl c.) HCN d.) PH3

a.) H20

Which of the following is expected to have the highest boiling point? a.) CH4 b.) CH3Cl c.) CH2OH d.) C2H6

c.) CH2OH

Which of the following substances would not exhibit any hydrogen bonding interactions in a pure substance? a.) H20 b.) HF c.) N(CH3)3 d.) CH3CH2OH e.) CH3NH2

c.) N(CH3)3

In a pure sample of HF, what forces of attraction exist between the molecules?

dispersion forces, dipole-dipole interactions, and hydrogen bonds

Which of the following statements are true about nutritional calories: a.) 1 Calorie= 1,000 calories b.) 1 Calorie= 1 kcal c.) 1 Calories= 4.184 kJ d.) It is the amount of energy needed to raise the temperature of 1 kg of water 1°C e.) All of the choices are correct

e.) All of the choices are correct

What phase changes are exothermic?

freezing, condensation, deposition

What phase changes are endothermic?

melting, vaporization, sublimation

What do the variables in this equation stand for: q=mc△T

q= Heat/Energy (Cal/J) m= Mass (grams) c= Specific Heat Capacity △T= Change in Temperature