CHM 2032

A cup of whole milk contains 13g of carbohydrate, 9.0g of fat, and 9.0g of protein. How many kilocalories does a cup of milk contain?

13g *(4 carbs)=52 9.0g *(9 fat)=81 9.0g *(4 protein)=36 52+81+36=169 rounded to 170 kcal

Calculate the total heat in joules needed to convert 15.0g of liquid ethanol at 25.0*C to gas at its boiling point of 78.0*C. Ethanol has a specific heat of 2.46 J/g*C and a heat of vaporization of 841 J/g

15 * (78-25) * 2.46= 15 * 53 * 2.46=1956 J 15 * 841=12616 1956+12615=14,571 rounded to 14,600

How many calories are obtained from a pat of butter if it provides 150 J of energy when metabolized?

150 J *1cal/4.184 J=36 cal

When a volcano erupts 175g of steam at 100.00*C is released. How many kilojoules are lost when the steam condenses and then freezes at 0*C?

175 * 2260J/g=395,500+ 175 * 100 * 4.184=73,220+ 175 * 334=58,450 =527,170, rounded to 528kJ

Volume

1L=1000mL 1qt=2pt/4 cups 1dL=100mL 1gal=4qt 1mL=1cm^3 1mL=1cc

Time

1h=60min 1min=60s

Mass

1kg=1000g 1lb=16oz 1g=1000mg 1mg=1000mcg

Length

1km=1000m 1'=12in 1m=1000mm 1yd=3' 1cm=10mm 1mi=5280'

If your pace on a treadmill is 65 meters per minute, how many minutes will it take you to walk a distance of 7.5 kilometers?

1km=1000m or 10^3m 65m=1minute 7.5km*10^3m/1m*1min/65m=120min looks like this on calculator-7.5*10^3/65=115-round to 120

A rattlesnake is 2.44m long. How many centimeters long is the snake?

1m=100cm 100cm/1m and 1m/100cm 2.44m*100cm/1m=244cm

How many kilojoules (kJ) are released when 50.0g of steam from a volcano condenses at 100*C?

50.0g H20(gas)*2260J/1gH2O*1kJ/1o^3J=113kJ released

A-l

Aluminum

N-H-3

Ammonia -weak base

A-r

Argon

B-e

Beryllium

B

Boron

B-r

Bromine

C-a

Calcium

C

Carbon

C-l

Chlorine

C/u

Copper

Density

Density=mass/volume Density of solids, or liquids=g/cm^3 or g/mL, NOTE: 1mL=1cm^3 Density of gas= 1mL=1cm^3

Energy measurement

Energy is measured in the SI unit of energy and work: the joule (j) or in kilojoules (kJ), 1000 joules units of calories (cal) or in kilocalories (kcal), 1000 calories

F

Fluorine

giga

G=1,000,000,000 = 10^9

A-u

Gold

H-e

Helium

H

Hydrogen

I

Iodine

F-e

Iron

Changes of state

Liquid to gas: Heat of vaporization for water=540 cal/g (or 2260 J/g) requires a lot of energy Solid to liquid: Heat of fusion for water=80 cal/g (or 334 J/g)

L-i

Lithium

mega

M=1,000,000 = 10^6

M-g

Magnesium

The density of the zinc object is calculated from its mass and volume.

Mass of the zinc object=68.60, completely submerged in water the zinc object displaces its own volume of water from: 35.5mL of just water to and increase to 45.0mL water and zinc object. 45mL-3.5mL=9.5mL=9.5cm^3 Density of zinc= mass of zinc-68.60g/ volume of zinc-9.5cm^3=7.2g/cm^3

Hg

Mercury

N-e

Neon

N-i

Nickel

N

Nitrogen

O

Oxygen

P

Phosphorus

P-t

Platinum

K

Potassium

What is the specific heat if 24.8g of a metal absorbs 275J of energy and the temp rises from 20.2*C to 24.5*C?

STEP 1 Analyze the problem: state given and needed quantities Given: 24.8g metal - 275J energy - T-initial=20.2*C - T-final=24.5*C Needed: specific heat STEP 2 Calculate the temp change: 24.5-20.2=4.3 Write the heat equation: SH=Heat/m * T(change) SH=275J/24.8g*4.3*C=2.6J/g*C on calculator multiply denominator first and round to 107, then divide 275 by 107 for 2.57 rounded to 2.6

S-i

Silicon

A-g

Silver

N-a

Sodium

S

Sulfur

tera

T=1,000,000,000,000= 10^12

Converting between degrees Celsius and degrees Fahrenheit

Temperature equation to obtain degrees Celsius: TF-32/1.8 For instance: on a hot day the temp reached 95* F, what is the temp in C? 95-32/1.8 95-32=63 63/1.8=35 *C Temperature equation to obtain degrees Fahrenheit: TF=1.8(TC)+32 For instance, a patient has a temp of 39.7 *C, what is the temp in degrees Fahrenheit? 1.8*39.7=71.46 +32=103.46 rounded to 103.5 *F

S-n

Tin

T-i

Titanium

W

Tungsten

Heat equation

When we know the specific heat of a substance we can calculate the heat lost or gained by measuring its mass and temperature change: heat = mass * temp change * SH

An unknown liquid has a density of 1.32g/mL. What is the volume of a 14.7g sample of the liquid?

With density calculations substitute with the proportion formula: 14.7g/1.32g?mL=11.1mL liquid

How many joules are needed to melt 32.0g of ice at 0*C?

Write the heat conversion factor and any metric factor. 1g of H2O (solid -> liquid)=334J 334J/1g H2O and 1gH2O/334J How many joules are needed to melt 32.0g of ice at 0*C? 32.0g H2O(s)*334J/1gH2O(s)=10,700J

Zn

Zinc

C-H-3-C-O-2-H

acetic acid -acid in vinegar

Calories

are defined as the amount of of energy needed to raise the temperature of 1g of water by 1 degree *C 1cal=4.184J(exact) 4.184J/1cal - and 1cal/4.184J

H-C-O-3-

bicarbonate

centi

c=0.01 = 10^2

C-a-C-O-3

calcium carbonate -sea shell , rock

C-O-2

carbon dioxide -dry ice

C-O-3^2-

carbonate

ClO3-

chlorate

deci

d=0.1 = 10^-1

N-2-O

dinitrogen monoxide -laughing gas

H-C-l

hydrochloric acid -muriatic acid

H-2-O-2

hydrogen peroxide -antiseptic

Specific heat (SH)

is the amount of heat that raises the temp of exactly 1g of a substance by exactly 1 *C SH for H2O= 1.00cal/g *C = 4.184J/g *C

kilo

k=1,000 = 10^3

Typical energy values for the three food types

kcal/g kJ/g Carbohydrate 4 17 Fat 9 38 Protein 4 17

milli

m=0.001 = 10^-3

C-H-4

methane -natural gas

nano

n=0.000000001 = 10^-9

N-O-3-

nitrate

H-N-O-3

nitric acid -aqua fortis

O-3

ozone gas -in ozone layer

pico

p=0.000000000001 = 10^-12

P-O-4^3-

phosphate

K-M-n-O-4

potassium permanganate -clear water

S-i-O-2

silicon dioxide -silica, quartz

N-a-H-C-O-3

sodium bicarbonate -baking soda

N-a-C-l

sodium chloride -table salt

N-a-O-H

sodium hydroxide -strong base

S-O-4^2-

sulfate

H-2-S-O-4

sulfuric acid -acid in car battery

micro

u/mcg=0.000001 = 10^-6