Chem 101 Ch 1 text questions

formula for percent error

%error = (difference from known value)/known value X100%

How many m^3 are in 2.43 yd^3?

1.86 1meter = 1.0936yds (1m)^3 = (1.0936 yds)^3 1m^3 = 1.3079yds^3 2.43 yds^3 x 1m^3/1.3079yds^3 = 1.86m^3

big to small

100km, 100m, 100cm, 100nm

small to big

100nm, 100cm, 100m, 100km

Convert 2341 mm to nm. Use sig figs. Enter just the numerical value without units.

2.341E9 or 2341000000 * First convert 2341 mm to meters. The conversion factor is 10-3 meters on top and 1 mm on the bottom. 2341mm x 10^-3meters/1mm = 2.31meters Then, convert meters to nanometers. The conversion factor is 1 nm on top and 10-9 meters on the bottom. 2.341mX 1nm/10^-9m = 2.341 x 10^9 nm

How much will you spend in fuel to travel 405 miles? Your car gets on average 37 miles per gallon and gas costs $2.70/gallon. Report your answer to four significant figures. Enter just the numerical value without the dollar sign.

29.55 *405milesX 1gallon/37miles X $2.70/1gallon = $29.55

Convert 0.0003215 to scientific notation. Use "E" for "×10" followed by the power.

3.215E-4 or 3.2E-4 Because the decimal number is < 1, the power must be negative. So we have to move the decimal 4 places to the right in order to achieve a number ≥ 1

How many minutes does it take to travel 405 miles at a speed of 75 miles per hour? Use sig figs. Enter just the numerical value without units.

324 *405 miles × (1 hr)/(75 miles)×(60 minutes)/(1 hr)=324 minutes

Convert 341 dL to mL. Use sig figs, and do not use scientific notation. Enter just the numerical value without units.

34100 * 341dL x 10^-1L/1dL x 1mL/10^-3L = 34100mL

Convert 4356.143 to scientific notation. Use "E" for "×10" followed by the power.

4.356143E3 or 4.3E3 Explanation Because the decimal number is >1, the power must be positive. So we have to move the decimal 3 places to the left in order to achieve a number ≥ 1

Gases

Are highly dispersed

Fruit easily turns brown when exposed to air.

Chemical

Convert 4.653 × 10 ^−6 to a decimal number.

0.000004653 The decimal is moved 6 places to the left.

Report 0.02315621 to (3) sig figs.

0.0232 Three sig figs would be 0.023__. The digit to the immediate right of the "1" in 0.231 is ≥ 5, so we round up.

What is the % error of the boiling point measurement example? The boiling point of water is 100.0°C at sea level. Suppose you used a thermometer to measure a beaker of boiling water in the lab at sea level. The thermometer reads 99.8°C.

0.2 %error = 0.2/100 X100% = 0.2%

Carry out the following calculation with the correct number of sig figs. (431.00791 + 52.5441)/45.3200130

10.66972. The sum in the numerator is 483.55201. Because this is addition, we go by the fewest decimal places that need to be marked: 483.5520. Dividing this by the denominator, we get 10.66972355. The last step was division, which goes by the fewest sig figs present. 483.5520 has (7) sig figs, whereas 45.3200130 has (10) sig figs. So, the final answer is reported to (7) sig figs: 10.66972355 ~ 10.66972.

Convert 1.145 × 10^5 to decimal format.

114500 The decimal is moved 5 places to the right.

How many grams of water are contained in a 0.127 L sample at 20°C?

127 0.127L x 1mL/10^-3L x 0.99823g/1mL = 127grams

Convert 0.152 km to m. Enter just the numerical value without units.

152 * 0.152km X 1000meters/1km=152 meters

Carry out the following calculation with the correct number of sig figs. 431.00791 + 52.5441

483.552 There are four decimal places in 52.5441 that determine the number of decimal places in the answer. 483.55201 ≈ 483.5520 We round down because the "1" is < 5.

How many sig figs are in 0.00034210?

5 - The four left-most zeros do not count since they start the decimal number (rule 5). The final zero after the 1 does count as it is a trailing zero of a decimal number (rule 3).

San Francisco and Los Angeles are 385 miles apart. Assuming an average speed of 65 miles per hour, how long will it take for you to drive between the cities?

65 miles per hour = 65miles/1hr 65miles/1hr or hr/65 miles 385miles x 1hr/65miles = 5.9 hours

Carry out the following calculation with the correct number of sig figs. (24.324)(3.2122) - 9.3210

68.813. (24.324)(3.2122)-9.3210 =78.1335528-9.3210 = 68.8125528 = 68.8126

Which digit is uncertain in the measurement: 23.147 meters?

7 - The last digit in a measurement is uncertain.

How many sig figs are in 300.123940?

9 - The two zeros after the 3 count, since they are between nonzero digits (rule 2). The last zero counts since it is a trailing zero of a decimal number (rule 3).

Solids

Atoms closely packed together

Let's go back to (1.32451 - 0.341) and "tag" the last digit we would have kept. Because this is subtraction, we go by:

Fewest decimal places. In a subtraction step, the number of decimal places in the answer equals the fewest number of decimal places present.

We keep all digits, but "tag" the third significant figure from the left: 0.98351 Next, 0.98351(1.0054) = 0.9888209554. The last operation is multiplication, so we should go by:

Fewest sig figs. In a multiplication step, the number of significant figures in the answer equals the fewest number of significant figures present.

Liquids

Have volume but no shape

coffee latte is a homogeneous or heterogeneous mixture.

Heterogeneous mixture There are two separate layers in a cappuccino, indicating a non-uniform distribution of multiple compounds.

Identify the following as either a homogeneous or heterogeneous mixture. OOOOOO oooooooo OOOOOO oooooooo red and blue balls

Homogeneous mixture

Gaseous vapor observed when handling dry ice (solid CO2).

Physical

Sugar mixes very well with coffee. physical or chemical change.

Physical

The volume of water displaced equals which of the following?

The difference between the initial and final volumes. The volume of water displaced equals the difference between the initial and final volumes. For example: If the initial volume is 5 mL and the final volume is 8 mL, the volume of water displaced is 3 mL.

What kind of ruler would give the more reproducible result?

The ruler with the greater number of increments is more reliable.

Throughout the entire figure, exactly one red sphere is connected to two white spheres, showing the presence of

a pure compound.

Kelvin and _______ are on identical scales.

c*

Identify the following as either an element or a compound. square shaped tightly packed green and purple ((((((((( OOO ((((((((( OOO combines more than one element

compound

density formula

denisity = mass/volume = g/mL = g/cm^3

Identify the following as either an element or a compound. OOOOOOO OOOOOOO OOOOOOO

element

grams to mL

grams of water x Ml of water/grams of water = mL of water

The ______ the number of digits in a measurement, the more precise the reading.

larger

law or a theory. Two bodies attract each other with a force that is directly proportional to their masses but inversely related to their distance.

law Two bodies attract each other with a force that is directly proportional to their masses, but inversely related to their distance. (This statement summarizes a property of physical objects but offers no explanation)

nanometers to meters formula

nm x meters/nm = meters

6-month old baby who starts a diet of solid foods. The baby eats some meat, some vegetables, and some fruit. After a few days, the baby develops a rash. The parents obviously want to solve this problem as quickly as possible. The pediatrician suggests they feed the baby only one type of food at a time and monitor the baby's skin for a week. If all is clear, introduce a new food item and repeat. By changing only one item at a time, the cause of the allergy can be pinpointed. Is it absolutely certain that food caused the allergy?

no The probable cause is food, but there could be many other factors, such as a new type of clothing, soap, shampoo, etc. We'll return to this later when revision of the original guess is necessary.

According to the ruler, the indicated distance is greater than 2.5 cm but less than 2.6 cm. This is certain and indisputable. Is 2.5 cm correct?

no ruler clearly indicates a measurement > 2.5 cm.

Spheres of the same color indicate only

one element.

Sand is coarse - physical or chemical property.

physical

Throughout the entire cube, a regular pattern repeats, showing the presence of a

pure compound.

law or a theory? Through a process known as "panspermia" micro-organisms on asteroids crash landed on Earth 4 billion years ago thus seeding the planet with the origins of life

theory = Through a process known as "panspermia," micro-organisms on asteroids crash landed on Earth 4 billion years ago, thus seeding the planet with the origins of life. (This statement explains an observation by providing the underlying mechanism).

Two different colored spheres indicate

two different elements

Two different colored spheres indicate

two different elements.

dimensional analysis conversion

unit a to unit b to unit c unit aXunitb/unit a X unit c/unit b = unit c

According to the ruler, the indicated distance is greater than 2.5 cm but less than 2.6 cm. This is certain and indisputable. 2.53 cm correct?

yes 2.53 cm is acceptable, as it is between 2.5 and 2.6 cm.

According to the ruler, the indicated distance is greater than 2.5 cm but less than 2.6 cm. This is certain and indisputable. How about 2.54 cm?

yes as it is between 2.5 and 2.6 cm.