Key to the study of Chemistry

Use your descriptions in the previous problem to identify the physical state (at room temperature) of the following: (a) the air in your room; (b) tablets in a bottle of vitamins; (c) sugar in a packet.                         

Define physical property and chemical property. Identify each type of property in the following statements: (a) Yellow-green chlorine gas attacks silvery sodium metal to form white crystals of sodium chloride (table salt). (b) A magnet separates a mixture of black iron shavings and white sand

Which of the following is a chemical change? Explain your reasoning: (a) boiling canned soup; (b) toasting a slice of bread; (c) chopping a log; (d) burning a log.

Define physical change and chemical change. State which type of change occurs in each of the following statements: (a) Passing an electric current through molten magnesium chloride yields molten magnesium and gaseous chlorine. (b) The iron in discarded automobiles slowly forms reddish brown, crumbly rust.

Which of the following changes can be reversed by changing the temperature: (a) dew condensing on a leaf; (b) an egg turning hard when it is boiled; (c) ice cream melting; (d) a spoonful of batter cooking on a hot griddle?

Describe solids, liquids, and gases in terms of how they fill a container. Use your descriptions to identify the physical state (at room temperature) of the following: (a) helium in a toy balloon; (b) mercury in a thermometer; (c) soup in a bowl

Scenes A–D represent atomic-scale views of different samples of substances:

(a) Under one set of conditions, the substances in A and B mix, and the result is depicted in C. Does this represent a chemical or a physical change?

(b) Under the second set of conditions, the same substances mix, and the result is depicted in D. Does this represent a chemical or a physical change?

(c) Under the third set of conditions, the sample depicted in C changes to that in D. Does this represent a chemical or a physical change?

(d) When the change in part (c) occurs, does the sample have different chemical properties? Physical properties?

Explain the difference between mass and weight. Why is your weight on the Moon one-sixth that on Earth?

A steel ball-bearing with a circumference of $32.5 mm$ weighs $4.20 g$.What is the density of the steel in g/cm³ (V of a sphere = $\frac{4}{3}\pi r^3$  ; circumference of a circle =$2\pi r$ )?

The alchemical, medical, and technological traditions were precursors to chemistry. State a contribution that each made to the development of the science of chemistry.

How did the phlogiston theory explain combustion?

One important observation that supporters of the phlogiston theory had trouble explaining was that the calyx of a metal weighs more than the metal itself. Why was that observation important? How did the phlogistonist’s respond?

Lavoisier developed a new theory of combustion that overturned the phlogiston theory. What measurements were central to his theory, and what key discovery did he make?

How are the key elements of scientific thinking used in the following scenario? While making toast, you notice it fails to pop out of the toaster. Thinking the spring mechanism is stuck, you notice that the bread is unchanged. Assuming you forgot to plug in the toaster, you check and find it is plugged in. When you take the toaster into the dining room and plug it into a different outlet, you find the toaster works. Returning to the kitchen, you turn on the switch for the overhead light and nothing happens.

Why is a quantitative observation more useful than a non-quantitative one? 

Which of the following are quantitative?

(a) The Sun rises in the east. 

(b) A person weighs one-sixth as much on the Moon as on Earth. 

(c) Ice floats on water. 

(d) A hand pump cannot draw water from a well more than 34 ft deep.

Describe the essential features of a well-designed experiment.                                                                              

Write the conversion factor(s) for

  (a)in² to m²                (b) km² to cm²

(c)mi/h to m/s         (d) lb/ft³ to g/cm³

Describe the difference between intensive and extensive properties. Which of the following properties are intensive: (a) mass; (b) density; (c) volume; (d) melting point?

For each of the following cases, state whether the density of the object increases, decreases, or remains the same:

(a) A sample of chlorine gas is compressed.

(b) A lead weight is carried up a high mountain.

(c) A sample of water is frozen.

(d) An iron bar is cooled.

(e) A diamond is submerged in water.

Explain the difference between heat and temperature. Does 1 L of water at 65°F have more, less, or the same quantity of energy as 1 L of water at 65°C?

A one-step conversion is sufficient to convert a temperature in the Celsius scale into the Kelvin scale, but not into the Fahrenheit scale. Explain.

The average radius of a molecule of lysozyme, an enzyme in tears, is 1430 pm. What is its radius in nanometres (nm)?

The radius of a barium atom is $\mathbf{2}\mathbf{.}\mathbf{22}\mathbf{\times }{\mathbf{10}}^{\mathbf{-}\mathbf{2}}$m .What is its radius in angstrom $\left(°A\right)$?

What is the length in inches (in) of a 100.m soccer field?

The center on your basketball team is 6 ft 10 in tall. How tall is the player in millimeters (mm)?                       

A small hole in the wing of a space shuttle requires a $\mathbf{20}\mathbf{.}\mathbf{7}\mathbf{ }\mathit{c}{\mathit{m}}^{\mathbf{2}}$ patch.

(a) What is the patch’s area in square kilometres ( $\mathit{k}{\mathit{m}}^{\mathbf{2}}$)?

(b) If the patching material costs NASA $\mathbf{\$}{\raisebox{1ex}{$\mathbf{3}\mathbf{.}\mathbf{25}$}\!\left/ \!\raisebox{-1ex}{$\mathbf{i}\mathbf{n}\mathbf{c}\mathbf{h}$}\right.}^{\mathbf{2}}$ , what is the cost of the patch?

Write the conversion factor(s) for

  (a) cm/min to in/s         (b) m³  to in³

  (c) m/s²to km/h²         (d) gal/h to l/min

The area of a telescope lens is $\mathbf{7903}\mathbf{ }{\mathbf{mm}}^{\mathbf{2}}$.

(a) What is the area in square feet (${\mathbf{ft}}^{\mathbf{2}}$ )? 

(b) If it takes a technician 45 s to polish $\mathbf{135}\mathbf{ }{\mathbf{mm}}^{\mathbf{2}}$ , how long does it take her to polish the entire lens?                      

Express your body weight in kilograms (kg).

For each pair, which has higher potential energy? (a) The fuel in your car or the gaseous products in its exhaust (b) Wood in a fire or the ashes after the wood burns

For each pair, which has higher kinetic energy? (a) A sled resting at the top of a hill or a sled sliding down the hill (b) Water above a dam or water falling over the dam.

A small cube of aluminum measures 15.6 mm on a side and weighs 10.25 g. What is the density of aluminum in g/cm³?                                                         

(a) How many cubic meters of milk are in 1 qt (946.4ml)?

(b) How many liters of milk are in 835gal (1gal = 4qt) ?

An empty Erlenmeyer flask weighs 241.3 g. When filled with water ( d = 1.00 g/cm³ ), the flask and its contents weigh 489.1 g. (a) What is the flask’s volume? (b) How much does the flask weigh when filled with chloroform ( d = 1.48 g/cm³)?      

There are $\mathbf{2}\mathbf{.}\mathbf{60}\mathbf{\times }{\mathbf{10}}^{\mathbf{15}}$short tons of oxygen in the atmosphere (1 short ton = 2000 lb). How many metric tons of oxygen are present (1 metric ton = 1000 kg)?

The speed of light in a vacuum is $\mathbf{2}\mathbf{.}\mathbf{998}\mathbf{\times }{\mathbf{10}}^{\mathbf{8}}\mathbf{m}\mathbf{/}\mathbf{s}$ . What is its speed in (a) km/h; (b) mi/min ?

An empty vial weighs . (a) If the vial weighs  when filled with liquid mercury (d = 13.53g/cm³ ), what is its volume? (b) How much would the vial weigh if it were filled with water ( $\mathbf{d}\mathbf{ }\mathbf{=}\mathbf{ }\mathbf{0}\mathbf{.}\mathbf{997}\mathbf{ }\mathbf{g}\mathbf{/}{\mathbf{cm}}^{\mathbf{3}}\mathbf{ }\mathbf{at}\mathbf{ }\mathbf{25}\mathbf{°}\mathbf{C}$ )?

The volume of a certain bacterial cell is 2.56 mm³ . (a) What is its volume in cubic millimeters ( mm³ )? (b) What is the volume of 10⁵ cells in liters (L)?

The average density of Earth is 5.52 g/cm³. What is its density in (a) km/m³ ; (b) lb/ft³ ?

When you convert feet to inches, how do you decide which portion of the conversion factor should be in the numerator and which in the denominator?

Explain the difference between mass and weight. Why is your weight on the Moon one-sixth that on Earth?

A steel ball-bearing with a circumference of 32.5 mm weighs 4.20 g. What is the density of the steel in g/cm³ (V of a sphere = 4/3 πr³ ; circumference of a circle = 2πr)?

Write the following numbers in scientific notation: 

(a) 282.0

(b) 0.0380

(c) 4270.8

(d) 58,200.9

Write the following numbers in standard notation. Use a terminal decimal point when needed: 

(a)  $\mathbf{5}\mathbf{.}\mathbf{55}\mathbf{\times }{\mathbf{10}}^{\mathbf{3}}$

(b)  $\mathbf{1}\mathbf{.}\mathbf{0070}\mathbf{\times }{\mathbf{10}}^{\mathbf{4}}$

(c)  $\mathbf{8}\mathbf{.}\mathbf{85}\mathbf{\times }{\mathbf{10}}^{\mathbf{-}\mathbf{7}}$

(d)  $\mathbf{3}\mathbf{.}\mathbf{004}\mathbf{\times }{\mathbf{10}}^{\mathbf{-}\mathbf{3}}$

Write the following numbers in standard notation. Use a terminal decimal point when needed: 

(a)   $\mathbf{6}\mathbf{.}\mathbf{500}\mathbf{\times }{\mathbf{10}}^{\mathbf{3}}$

(b)  $\mathbf{3}\mathbf{.}\mathbf{46}\mathbf{\times }{\mathbf{10}}^{\mathbf{-}\mathbf{5}}$

(c) $\mathbf{7}\mathbf{.}\mathbf{5}\mathbf{\times }{\mathbf{10}}^{\mathbf{2}}$

 (d)   $\mathbf{1}\mathbf{.}\mathbf{8856}\mathbf{\times }{\mathbf{10}}^{\mathbf{2}}$       

Which procedure(s) decrease(s) the random error of a measurement: (1) taking the average of more measurements; (2) calibrating the instrument; (3) taking fewer measurements? Explain

What is an exact number? How are exact numbers treated differently from other numbers in a calculation?

The distance between two adjacent peaks on a wave is called the wavelength. (a) The wavelength of a beam of ultraviolet light is 247 nanometres (nm). What is its wavelength in meters? (b) The wavelength of a beam of red light is 6760 pm. What is its wavelength in angstroms( $\mathbf{\AA }$ )?

Each of the beakers depicted below contains two liquids that do not dissolve in each other. Three of the liquids are designated A, B, and C, and water is designated W.                             

(a) Which of the liquids is (are) more dense than water and which less dense?

(b) If the densities of W, C, and A are 1.0 g/mL, 0.88 g/mL, and 1.4 g/mL, respectively, which of the following densities is possible for liquid B:

$\mathbf{0}\mathbf{.}\mathbf{79}\mathbf{ }\raisebox{1ex}{$\mathbf{g}$}\!\left/ \!\raisebox{-1ex}{$\mathbf{ml}$}\right.\mathbf{,}\mathbf{ }\mathbf{0}\mathbf{.}\mathbf{86}\mathbf{ }\raisebox{1ex}{$\mathbf{g}$}\!\left/ \!\raisebox{-1ex}{$\mathbf{ml}$}\right.\mathbf{,}\mathbf{ }\mathbf{0}\mathbf{.}\mathbf{94}\mathbf{ }\raisebox{1ex}{$\mathbf{g}$}\!\left/ \!\raisebox{-1ex}{$\mathbf{ml}$}\right.\mathbf{,}\mathbf{ }\mathbf{1}\mathbf{.}\mathbf{2}\mathbf{ }\raisebox{1ex}{$\mathbf{g}$}\!\left/ \!\raisebox{-1ex}{$\mathbf{ml}$}\right.$ ?

Perform the following conversions:

$$\begin{gathered} \mathbf{\left(}\mathbf{a}\mathbf{\right)}\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{68}\mathbf{ }\mathbf{°}\mathbf{F}\mathbf{ }\mathbf{(}\mathbf{a}\mathbf{ }\mathbf{pleasant}\mathbf{ }\mathbf{spring}\mathbf{ }\mathbf{day}\mathbf{)}\mathbf{ }\mathbf{to}\mathbf{ }\mathbf{°}\mathbf{C}\mathbf{ }\mathbf{and}\mathbf{ }\mathbf{K}\mathbf{ } \\ \mathbf{\left(}\mathbf{b}\mathbf{\right)}\mathbf{ }\mathbf{ }\mathbf{164}\mathbf{°}\mathbf{C}\mathbf{ }\mathbf{(}\mathbf{the}\mathbf{ }\mathbf{boiling}\mathbf{ }\mathbf{point}\mathbf{ }\mathbf{of}\mathbf{ }\mathbf{methane}\mathbf{,}\mathbf{ }\mathbf{the}\mathbf{ }\mathbf{main}\mathbf{ }\mathbf{component}\mathbf{ }\mathbf{of}\mathbf{ }\mathbf{natural}\mathbf{ }\mathbf{gas}\mathbf{)}\mathbf{ }\mathbf{to}\mathbf{ }\mathbf{K}\mathbf{ }\mathbf{and}\mathbf{ }\mathbf{°}\mathbf{F}\mathbf{ } \\ \mathbf{\left(}\mathbf{c}\mathbf{\right)}\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{0}\mathbf{ }\mathbf{K}\mathbf{ }\mathbf{(}\mathbf{absolute}\mathbf{ }\mathbf{zero}\mathbf{,}\mathbf{ }\mathbf{theoretically}\mathbf{ }\mathbf{the}\mathbf{ }\mathbf{coldest}\mathbf{ }\mathbf{possible}\mathbf{ }\mathbf{temperature}\mathbf{)}\mathbf{ }\mathbf{to}\mathbf{ }\mathbf{°}\mathbf{C}\mathbf{ }\mathbf{and}\mathbf{ }\mathbf{°}\mathbf{F} \end{gathered}$$