Ch. 2 section 1-2 answers

What are base units? They are defined units in a system of measurements. A base unit is independent of other units.

Provide the seven base units of SI. Seconds for time Meters for length Kilogram for mass Kelvin for Temperature Mole for Amount of substance Ampere for electric current Candela for luminous intensity

What are derived units? They are measurements that combines base units Volume - cm3 Speed- m/s Density- g/cm3

Define density Density is the ratio that compares the mass of an object to its volume. Density- g/cm3

Displacement of water from 20 to 40 gives us the volume of 20 mls. 1. A piece of matter with a mass of 147 g is placed in a 50 mL graduated cylinder. The water level rises from 20mL to 40 mL. What is the density of the metal? Displacement of water from 20 to 40 gives us the volume of 20 mls. Density = mass/volume 147g / 20ml = 7.35 g/ml

So we are missing the volume D=m/x 4g = 20g 1ml Xml 2. What is the volume of a sample that has a mass of 20 g and a density of 4g/mL? So we are missing the volume D=m/x 4g = 20g 1ml Xml Cross multiply and divide 4g xml = 20g/ml = 4g 4g 5 ml

Aluminum’s density is 2.7 g/ml 20g = 4 g/cm3 5 cm3 3. A metal cube has a mass of 20 g and a volume of 5cm3. Is the cube made of pure aluminum? Explain you answer. See practice problem help. Aluminum’s density is 2.7 g/ml 20g = 4 g/cm3 5 cm3 No, this is not pure aluminum

What is the Kelvin scale, where does chemistry use this measurement? It’s the SI base unit of temperature where 273K is the freezing point of water and the boiling point of water is 373K Kelvin is used in describing the behavior of gases.

Convert the following 450 °C to ___________K Convert the following 450 °C to ___________K 25K___________°C 3°C to _____________K 600K___________°C 0°C to _____________K 0K___________°C -60°C to___________K 375K___________°C *Celsius to Kelvin add 273 *Kelvin to Celsius subtract 273 723 -248 276 327 273 -273 213 102

What is scientific notation? Scientific notation expresses numbers as multiple of two factors: A number between 1 and 10 And ten raise to a power, exponent The exponent tells you how many times the first factor must be multiplied by ten. When numbers larger than 1 Power of 10 is in the positive When numbers smaller than 1 Power of 10 is in the negative

What is scientific notation? 700m 38000m 4500000m 685000000000m 0.0054kg 0.00000687kg g. 0.000000076 kg h. 0.0000000008kg 7x 102 m 3.8 x 104 m 4.5 x 106 m 6.85 x 1011 m 5.4 x 10-3 kg 6.87 x 10-6 kg 7.6 x 10-8 kg 8 x 10-10 kg

What is the rule when adding or subtracting exponents? When adding or subtracting numbers written in scientific notation, you must be sure that the exponents are the same before doing the arithmetic.

14. Read instructions and solve. a 14. Read instructions and solve. a. 5 X 10-5m + 2 X 10-5m = _____________________ b 7 X108m – 4X108m = _______________________ e. 1.26 X 104 kg + 2.5 X103kg __________________ g. 4.39 X 105kg – 2.8 X 104kg ___________________ 7 x 10-5 m 3 x 108 m 15.1 x 103 kg Change exponents to be the same 1.51 x 104 kg 12.6 x 103 kg 4.11 x 105 kg Change exponents to be the same 0.28 kg x 105 kg

What is the rule when multiplying or dividing exponents? For multiplication, you multiply the first factors. Then, you add the exponents. For division, you divide the first factors. Then, you subtract the exponent of the divisor from the exponent of the dividend.

15. Read instructions and solve. a. 4 X 102cm x 1 X 108cm = c 15. Read instructions and solve. a. 4 X 102cm x 1 X 108cm = c. 3 X101 cm x 3 X10-2cm = 16b. 8 X 104 g ÷ 4 X101 cm3 = d. 4 X 10-3g ÷ 2 X 10-2 cm3 = 4 x 1010 cm2 9 x 10-1 cm2 2 x 103 g/cm 2 x 10-1 g/cm

What is a conversion factor? A conversion factor is a ratio of equivalent values used to express the same quantity in different units. A conversion factor is always equal to 1.

19. How many seconds are there in 24 hours? Place the units you want to get rid of across from each other Place starting amount here 24 hours -------- 60 minutes -------------- 60 seconds = 86,400 sec 8.64 x 104 sec -------------- 1 hour 1 minutes -------------- Place conversion factor here Place conversion factor here

Place starting amount here 20. A car is traveling 90.0 kilometers per hour. What is its speed in miles per minute? One kilometer = 0.62 miles. Place the units you want to get rid of across from each other Place starting amount here 90 km -------- 0.62 miles 1 hour ------------- = 0.93 miles/min 9.3 x 10-1 miles/min 1 hour 1 km -------------- ------------- 60 minutes Place conversion factor here Place conversion factor here

The Metric System Base Units Length meter Mass gram Time seconds

kilo 1000 hecta 100 deca 10 Base 1 deci 0.1 centi 0.01 milli 0.001 Prefix kilo 1000 hecta 100 deca 10 Base 1 deci 0.1 centi 0.01 milli 0.001

Put in the prefix Prefix + base = measurement kilo- meter 1000 meters centi- liter 0.01 liters deca- gram 10 grams

0.03 hm 3 Conversions kilo hecta deca Base deci centi milli 300. centimeters = hm Move the decimal point toward the prefix you want. 0.03 hm The decimal moved to the left 4 times 3

25 kilograms to _______________ decigrams Practice kilo hecta deca Base deci centi milli 250000 25 kilograms to _______________ decigrams Where do we start? Kilo Where do we end? deci How many spots and which direction? 4 to the right

0.0043 grams to _______________ hectagrams 0.000043 Practice kilo hecta deca Base deci centi milli 0.0043 grams to _______________ hectagrams 0.000043 38.508 38508 meters to _______________ kilometers 0.00134 1.34 milliliters to _______________ liters 0.9756 975.6 liters to _______________ kiloliters

Scientific Notation Used to express really big or small numbers Really big- power of 10 is in the positive Really small- power of 10 is in the negative You move the decimal point behind the first NON ZERO number.

Practice 1392000 km Is this a big number or small? Is my power of 10 in the positive or negative? Where does the decimal go? 1.392 x 106 km

Practice Scientific Notation 0.000003457 grams 3.457 x 10-6 grams 48000 meters 4.8 x 104 meters 0.0002563 meters 2.563 x 10-4 meters 0.00000000967meters 9.67 x 10-9 meters 8,900,000,000,000 kilometers 8.9 x 1012 km

Adding & Subtracting Scientific Notation Make sure that the exponents are the same! 1.3 x 10-2 kg + 2.5 x 10-2 kg = 3.487 x 104 kg + 3.785 x 105 kg = Change them to match (doesn’t matter which) 0.3487 x105kg + 3.785 x 105 kg = 3.8 x 10-2 kg 4.1337 x 105kg (is this correct??) 4.134 x 105kg (is this correct??)

Practice 7 x 10-5 m 5 x 10-5 m + 2 x 10-5 m = 1.26 x 104 kg + 2.5 x 103 kg = 1.5 x 104 kg 9 x 102 m -- 7 x 102 m = 2 x 102 m 5.36 x 10-1 km – 7.40 x 10-2 km = 4.62 x 10-1 km

Multiplying Scientific Notation Multiply the factors first!! Then add the exponents Take care in assigning the sign to the exponent Adding +3 to +4 = 7 but +3 to -4 = -1 Subtracting -6 from -4 = 2 but -4 from -6 = -2 (2 x 103 kg) X (3 x 102 kg) = Rule 1 = 6 Rule 2 =105 6 x 105 kg2

Practice Multiplying Scientific Notation (4 x 102 cm) (1 x 108 cm) = 4 x 1010 cm2 (3 x 101 cm) (3 x 10-2 cm) = 9 x 10-1 cm2 (1 x 103 cm) (5 x 10-1 cm) = 5 x 102 cm2

Dividing Scientific Notation Divide the factors first!! Then subtract the exponent of the divisor from exponent of the dividend (9 x 108 kg) ÷ (3 x 10-4 kg) = Rule 1: 9 ÷ 3 = 3 Rule 2: 8 - -4 = 12 3 x 1012 kg

Practice Dividing Scientific Notation (6 x 102 g) ÷ (2 x 101 g) = 3 x 101 g (9 x 105 cm) (3 x 10-1 cm) = 3 x 106 cm (4 x 10-3 cm) (2 x 10-2 cm) = 2 x 10-1 cm