CHEM 123 Sapling Learning Chapter 1

Ethanol is a common laboratory solvent and has a density of 0.789 g/mL. What is the mass, in grams, of 125 mL of ethanol? mass: g

98.6 g

Which of the following are mixtures?

air (mostly N2 and O2) salt water Pure substances can be represented by a single chemical formula. In contrast, mixtures require multiple chemical formulas to represent their composition. Salt is a pure substance because it can be represented by a single chemical formula, NaCl. Water is a pure substance because it can be represented by a single chemical formula, H2O. Salt water would need more than one chemical formula to describe its compositon, NaCl and H2O, so it is a mixture. Air, rather than being a compound of nitrogen and oxygen, is a mixture of nitrogen and oxygen as indicated by its two distinct chemical formulas, N2 and O2. Examples of compounds of nitrogen and oxygen include NO and NO2.

Label the zeros in this number as either significant or not significant. 0.020

not significant; not significant; significant The first two zeros in this number are leading zeros because they come before the 2. Leading zeros are never significant. The last zero in this number is a trailing zero because it comes after the 2. Because a decimal point is shown in this number, the trailing zeros are significant.

Convert 7.81 cm3 to gallons. 7.81 cm3= gal

0.00206 gal

Steve races to the nearest taco stand at lunchtime and sees that his pedometer recorded his peak speed at 107.1 cm/s. What was Steve's peak speed in kilometers per hour? peak speed = km/h

3.856 km/h Four conversion factors are needed to convert 107.1 cm/s to the equivalent speed in kilometers per hour. Recall that 1 m=100 cm and 1 km=1000 m. Also there are 60 s in 1 min and 60 min in 1 h. Use the conversion factors to simultaneously convert centimeters per second to kilometers per hour. Arrange the conversion factors so that all units besides kilometers and hours cancel out. 107.1cm/s × 1m/100cm × 1km/1000m × 60s/1min × 60min/1h = 3.856kmh

Charlotte is driving at 50.1 mi/h and receives a text message. She looks down at her phone and takes her eyes off the road for 4.41 s. How far has Charlotte traveled in feet during this time? distance:

324 ft

Convert 162.4 ∘F to kelvins. temperature: K

345.6 K

A liquid has a volume of 0.0044 L. Convert this volume to cubic centimeters. 0.0044 L= cm^3

4.4 cm^3

Convert the given lengths from meters to the indicated derived units. 1.47 m to kilometers 0.00708 m to nanometers 12.9 m to centimeters

0.00147 km; 7080000 nm; 1290 cm Useful metric prefixes to remember include: Mega = 106; kilo = 103; deci = 10−1; centi = 10−2; milli = 10−3; micro = 10−6; nano = 10−9. To convert from the derived units to the base unit, you multiply by the prefix value. To convert the base unit to the derived unit, you divide by the prefix value. 1.47 m × 1km/10^3 m = 0.00147 km 0.00708 m × 1nm10^−9 m = 7.08×106 nm 12.9 m × 1cm10^−2m = 1290 cm

The volume of a sample of gas is measured as 4763.1 cm3. Convert the volume to cubic meters. 4763.1 cm^3=

0.0047361 m^3

Consider a cloudless day on which the sun shines down across the United States. If 2153 kJ of energy reaches a square meter (m2) of the United States in one hour, how much total solar energy reaches the entire United States per hour? The entire area of the United States is 9,158,960 km2.

1.972×10^16 kJ/h First convert the area of the United States from square kilometers (km2) to square meters (m2). The necessary conversion factor is 10002 m2 per 12 km2. 9158960 km2 × 10002m 212km2 = 9.159 × 1012 m2 Use the area of the United States to determine the amount of solar energy reaching that total area per hour given that 2153 kJ of energy reaches one square meter per hour. 9.159×1012 m2×2153 kJm2⋅h=1.972×1016kJh

The Empire State building in New York City is approximately 1250 ft tall. How many U.S. nickels would be in a stack of the same height? Each nickel is 1.95 mm thick. number of nickels: Each nickel has a mass of 5.000 g. How much would the stack of nickels from the previous question weigh? What is the value, in dollars, of the same stack of nickels? The 2017 U.S. gross domestic product (GDP) was valued at 19,390,604,000 dollars. How many Empire State building‑height stacks of nickels are needed to match the GDP in value? number of stacks:

number of nickels: 195385; mass: 976925g; value: 9769 dollars; 1984912

Complete each of the definitions with the appropriate phrase. Precision means that measurements are close to . Accuracy means that measurements are close to .

several; each other; individual; an accepted value For a measurement to be precise, several measurements must first be made. Then, those measurements must closely agree with each other. For a measurement to be accurate, it must agree with an accepted, or standard, value. An accurate measurement is not always precise, and a precise measurement is not always accurate.

Convert a speed of 801 mi/h to units of feet per minute. Also, show the unit analysis by dragging components into the unit‑factor slots. 801 mi/1h × (/)×(/) 801 mi/h=

(5280 ft/ 1 mi); (1 hr/60 mins) 70488 ft/min Unit analysis builds on two basic mathematical rules. When the numerator and denominator of a fraction are equal, the fraction has a value of 1. You can multiply anything by 1 without changing its value. When performing a unit analysis, make sure each set of parentheses is a valid unit factor. In other words, the numerator must be equal to the denominator. For example, 5280 ft=1 mi and 1 h=60 min. These equalities make up the unit factors for this problem. The goal for the numerator is to cancel out units of miles and end up with units of feet. Thus, miles has to appear in the denominator and feet has to appear in the numerator. The goal for the denominator is to cancel out units of hours and end up with units of minutes. Thus, hours has to appear in the numerator and minutes has to appear in the denominator.

Convert the given masses from the derived units to grams. 16.1 mg = 7.91 dg = 0.0387 μg =

0.0161 g; 0.791g; 3.87×10^−8g Useful metric prefixes to remember include: Mega=10^6 kilo=10^3 deci=10-1 centi=10-2 milli=10-3 micro=10-6 nano=10−9 To convert from the derived units to the base unit, you multiply by the prefix value. To convert the base unit to the derived unit, you divide by the prefix value. 16.1 mg × 10−3g/1mg = 0.0161 g 7.91 dg × 10−1g/1dg = 0.791 g 0.0387 μg × 10−6g/ 1μg = 3.87×10−8 g

Carry out the given conversions from one metric unit of mass to another. 11.5 dg= 0.355 cg=

1150 mg; 3.55 × 10^−6 kg Useful metric prefixes to remember include: Mega = 106; kilo = 103; deci = 10−1; centi = 10−2; milli = 10−3; micro = 10−6; nano = 10−9. One way to convert from one derived unit to another is by doing the conversion in two steps. First, to convert from the derived units to the base unit, you multiply by the prefix value. Second, to convert the base unit to the new derived unit, you divide by the prefix value. 11.5 dg × 10^−1g/1 dg = 1.15g then 1.15g × 1mg10^−3g = 1150 mg 0.355cg × 10^−2g/1cg = 0.00355g then 0.00355g × 1kg10^3g = 3.55×10−6 kg The calculations can also be combined into one step, making sure the units cancel. 11.5dg × 10^−1g/1dg × 1mg10^−3g = 1150 mg 0.355cg × 10^−2g/1cg × 1kg/10^3g = 3.55×10^−6 kg

A new linear temperature scale, degrees Zunzol ( ∘Z ), is based on the freezing point and boiling point of a newly discovered compound zunzol. The freezing point of zunzol, −141.5 ∘C, is defined as 0 ∘Z, and the boiling point of zunzol, −24.8 ∘C, is defined as 100 ∘Z. What is the freezing point of water in degrees Zunzol? freezing point: What is the boiling point of water in degrees Zunzol? boiling point:

121∘Z; 207∘Z To determine the freezing point of water in degrees Zunzol, you first need to determine the relationship between degrees Celsius and degrees Zunzol. Begin by writing the freezing and boiling points of zunzol in degrees Celsius and degrees Zunzol as 𝑥 and 𝑦 coordinates, where 𝑥 is the temperature in degrees Celsius and 𝑦 is the temperature in degrees Zunzol. (−141.5,0) and (−24.8,100) The Zunzol temperature scale is linear and the temperature in degrees Zunzol depends on the temperature in degrees Celsius. Therefore, write the relationship between degrees Celsius (𝑦) and degrees Zunzol (𝑥) using the generic formula for a line, 𝑦=𝑚𝑥+𝑏 where 𝑚 is the slope of the line and 𝑏 is the 𝑦-intercept. Use the 𝑥 and 𝑦 coordinates to calculate the slope, 𝑚, by dividing the change in 𝑦 by the change in 𝑥. 𝑚=𝑦2−𝑦1𝑥2−𝑥1=100−0−24.8−(−141.5)=0.8569 Then, calculate the 𝑦-intercept, 𝑏, using one of the coordinates, the value of 𝑚, and the generic equation for a line. 𝑦100100121=𝑚𝑥+𝑏=(0.8569)(−24.8)+𝑏−(0.8569)(−24.8)=𝑏=𝑏 Therefore, the relationship between degrees Celsius and degrees Zunzol can be described by the formula 𝑦=0.8569𝑥+121 or 𝑇Z=(0.8569)𝑇C+121 Use this relationship to convert the freezing point of water, 0 ∘C, to degrees Zunzol. 𝑇Z=(0.8569)(0)+121=121 ∘Z Use the same relationship to convert the boiling point of water, 100 ∘C, to degrees Zunzol. 𝑇Z=(0.8569)(100)+121=207 ∘Z

Mercury, also known as quicksilver, is a metallic element and a liquid at room temperature. Calculate mercury's density if a sample of mercury is found to have a mass of 365.0 g and a volume of 26.98 mL. density: g/mL

13.5 g/mL

A liquid solvent is added to a flask containing an insoluble solid. The total volume of the solid and liquid together is 91.0 mL. The liquid solvent has a mass of 23.7 g and a density of 0.865 g/mL. Determine the mass of the solid given its density is 2.75 g/mL. mass: g

175 g

Select the conversion factors needed to convert the speed of a car from kilometers per hour to miles per minute. 88.3 km/1 hr × × =0.915 mi/1 min

1mi/1.609km × 1hr/60 min To convert from kilometers per hour to miles per minute, you must perform two calculations. First, convert the distance traveled in kilometers to miles. Kilometers is in the numerator of the given value and therefore, should be placed in the denominator of the conversion factor to cancel out. Miles is in the numerator of the final value, and should be placed in the numerator of the conversion factor. The speed is now in miles per hour. Next, convert the time from hours to minutes. Hours is in the denominator of the given value and therefore should be placed in the numerator of the conversion factor to cancel out. Minutes is in the denominator of the final value, and should be placed in the denominator of the conversion factor. The calculation can be combined into a single step.

Round each number to two significant figures. 233.356: 0.002353: 1.005:

230; 0.0024; 1.0 There are five rules for determining which digits are significant in a number. 1. All nonzero digits are considered significant. For example, 234.56 has five significant figures: 2, 3, 4, 5, and 6. 2. Zeros appearing anywhere between two nonzero digits are significant. For example, 201.34 has five significant figures: 2, 0, 1, 3, and 4. 3. Leading zeros are not significant. For example, 0.00023 has two significant figures: 2 and 3. 4. Trailing zeros in a number showing a decimal point are significant. For example, 23.4500 has six significant figures: 2, 3, 4, 5, 0, and 0. 5. If the leftmost digit dropped is the number five or greater (5 through 9), round up.

To how many significant figures should each answer be rounded? equation A: (6.626× 10−34 J⋅s)(2.9979× 108 m/s)/4.470×10−7 m=4.443866979866×10−19 J(unrounded) After rounding, the answer to equation A should have: equation B: (6.022× 1023 atoms/mol)(0.889 g)/20.18 g/mol=2.653×1022 atoms(unrounded) After rounding, the answer to equation B should have

4 significant figures.; 3 significant figures. The number in the equation with the fewest significant figures limits the number of significant figures in the answer. In equation A, there are 4 significant figures in the numbers 4.470×10−7 and 6.626×10−34 . The number 2.9979×108 has 5 significant figures. The result of the calculations gives an answer that should have 4 significant figures. In equation B, the number 0.889 has only 3 significant figures, which limits the answer to 3 significant figures.

The surface temperature on Venus may approach 749 K. What is this temperature in degrees Celsius? 749 K = The temperature on Mercury may drop to −273 °F at night. What is this temperature in degrees Celsius? −273 °F =

476 °C; −169 °C

Red gold is a gold‑copper alloy used to make jewelry. A piece of jewelry made of red gold weighs 9.40 g and has a volume of 0.702 cm3. Gold has a density of 19.3 g/cm3 and copper has a density of 8.96 g/cm3. Calculate the percentage by mass of each metal in the jewelry. Assume the total volume of the jewelry is the sum of the volumes of the two metals it contains. gold: % copper: % Pure gold is defined as having 24 carats. When mixed in an alloy, the carats of gold are given as a percentage of this value. For example, a piece of jewelry made with 50% gold has 12 carats. State the purity of this piece of red gold jewelry in carats. purity: carats

61.7%: 38.3%; 14.8 carats

You just competed in a track meet and you ran the 1500 m race in 443 s. What was your average speed in miles per hour? speed: mph

7.574 mph Use 1 mi=1.609 km for the English to metric conversion. Other helpful conversion factors include 1 hr=60 min=3600 s and 1 km=1000 m. Use the conversion factors to simultaneously convert meters per second to miles per hour. Be sure that all units other than miles and hours cancel out. 1500m/443s × 1km/1000m × 1mi/1.609km × 60s/1min × 60min/1hr = 7.58 mph.

Perform the calculation and report the answer using the proper number of significant figures. Make sure the answer is rounded correctly. 1.012×10−3 J/(0.010456 g)(298.3682−298.3567)K =

8.42 J/g⋅K First, perform the subtraction step, but do not round the result. Instead, note the number of significant figures that the difference should have, and apply that restriction at the end of the calculation. (298.3682−298.3567)K = 0.0115 K This quantity has three significant figures. Now, perform the full calculation, keeping in mind that the quantity in parentheses has three significant figures. Since the other values being multiplied or divided have four or five significant figures, the final answer should be rounded to three significant figures. 1.012×10−3 J/(0.010456 g)(298.3682−298.3567)K=8.42 Jg·K Notice the dramatic reduction in the number of significant figures that can result from calculations involving subtraction.

Which of the changes are chemical changes?

A candle is burned. A silver teapot turns black. Two clear colorless salt solutions are mixed and a bright orange precipitate forms. Melting candle wax is only a phase change. The candle wax will turn solid again when the temperature is lowered. Burning a candle is a chemical change. The candle wax disappears, and gases and soot appear. The black coating on a silver teapot is primarily silver sulfide. It is a new substance, so its formation is a chemical change. The formation of a bright orange precipitate from a clear solution is evidence of a new substance being formed. The new substance has a different color and solubility from whatever was originally in the clear solutions. Therefore, this is a chemical change. Breaking solids into smaller pieces does not change the nature of the solid material. This is a physical change.

Match each definition to a type of energy.

Chemical: Energy derived from substances reacting and bonds being made or broken Electrical: Energy derived from moving charged particles Mechanical: Energy derived from the position and movement of an object Radiant: Energy derived from the visible and invisible electromagnetic spectrum Energy can take many different forms that are important in biological systems. One of the forms of energy that is most important to life is the body's ability to take in nutrients and convert them into an energy source. This is an example of chemical energy, wherein energy is derived from substances reacting and the bonds between atoms being made or broken, which transfers energy. For example, molecules such as glucose can be broken down into simpler molecules, which is a process that releases energy that was stored in the chemical bonds. Electrical energy can take different forms, but in each case, electrical energy is derived from the movement of charged particles. In an organism, charged ions can move across cell membranes and across concentration gradients, thereby generating electrical energy. This method of electrical energy generation forms the basis of the nervous system. Most organisms possess the capacity for locomotion, which is a type of mechanical energy. Specifically, mechanical energy is derived from the position and movement of an object. For example, the muscles, ligaments, and tendons can store and then release mechanical energy to produce movement. Even at the microscopic level, single-celled organisms with flagella or cilia can use mechanical energy to move around their environment. Radiant energy comprises the energy that collectively makes up the electromagnetic spectrum, such as visible light, infrared, ultraviolet, radio waves, and gamma rays. The energy is said to be radiant because the energy takes the form of rays or waves that are emitted and tend to radiate out from their source, just as heat in the form of infrared energy radiates out from our bodies. Electromagnetic radiation also forms the basis for vision, and ultraviolet wavelengths are some of the most common causes of mutation and cancer in organisms.

Put the steps in order to describe an experiment that follows the scientific method.

First make initial observation form initial hypothesis test initial hypothesis testing discredits initial hypothesis revise hypothesis test revised hypothesis testing confirms revised hypothesis the revised hypothesis may eventually become a theory Last The scientific method begins with an observation, followed by a hypothesis to explain the observation. The hypothesis then gets tested and revised and retested as needed. Once confirmed, the hypothesis is not necessarily called a theory. But after multiple confirmations by multiple people, a hypothesis may be accepted as a theory by the scientific community.

General Chemistry fourth edition by McQuarrie, Rock, and Gallogly. University Science Books presented by Macmillan Learning. Several groups of students are attempting to determine the density of a lead weight by various methods. Their data is shown in the table. A handbook lists the density of lead as 11.3 g/mL. Group 1 Group 2 Group 3 Measured density (g/mL), trial 1 11.5 11.5 10.9 Measured density (g/mL), trial 2 11.3 11.4 11.3 Measured density (g/mL), trial 3 11.1 11.4 11.1 Average density (g/mL) 11.3 11.4 11.1 Which group was most accurate? Which group was most precise?

Group 1; Group 2 Accuracy is how close a measured value is to the true or accepted value. In this case, the measured value is the average of the measured densities, and the true or accepted value is 11.3 g/mL. Since Group 1 had an average of 11.3 g/mL, they were the most accurate. Precision is how closely a set of values agree with each other. Group 2 showed the smallest difference between individual measurements, and so they were the most precise.

Classify each description as a hypothesis, theory, or law.

Hypothesis: an untested explanation an entomologist predicts Theory: an explanation that has been tested and verified Scientists after many experiments explain how Law: a description that explains what happens, but does not explain how A hypothesis is an educated guess, or an untested explanation, that is based upon observations or known facts. For example, if an entomologist guesses why gray moths survive better on gray tree trunks, but has not conducted any experiments to confirm this guess, she has constructed a hypothesis. This hypothesis can be tested in one or more experiments or tests. If a hypothesis has been repeatedly tested and verified by other scientists, it may become accepted as a theory. Theories offer a deeper and broader explanation of observations and laws. An example of a theory is kinetic molecular theory which explains the behavior of gases. A law describes past observations and can be used to predict future observations, but it does not explain how it happens. Examples include the law of gravity and the law of conservation of mass.

Classify each property as physical or chemical.

Physical properties: melting point color boiling point conductivity Chemical properties: susceptibility to rust flammability An intensive property is independent of the amount of substance present. An extensive property depends on the amount of substance present. Weight (mass), length, and volume are all extensive properties because they depend on the amount of substance present. For example, a large sample of salt would weigh more than a small sample of salt. Boiling point, melting point, density, temperature, color, and hardness are all intensive properties because they do not depend on the amount of substance present. For example, a large sample of salt is the same color as a small sample of salt.

in each of the images, two blocks are attached to a balance. Use the position and size of the blocks to determine which block is more dense in each image. A scale weighs two boxes. The green box on the left has a large volume and pulls lower on the scale. The blue box on the right has a smaller volume and is higher on the scale. Which block is more dense in the first image? Which block is more dense in the second image? Which block is more dense in the third image? First image: Green block is larger and heavier than the blue block. Second image: Blue and green block are the same size, but blue is heavier Third image: Green block is smaller and heavier than the blue block

The relative densities of the blocks cannot be determined. The blue block on the right is more dense. The green block on the left is more dense. Density is defined as the mass of a substance per unit volume. density=mass/volume Each image shows two blocks attached to a balance. Based on the positions of the blocks relative too each other, you can determine which block has a greater mass. Based on the sizes of the blocks, you can determine which block has a greater volume. The relative densities of the two blocks in each image can then be determined by comparing the mass and volume of each block. Based on the density equation, if the the blocks have the same volume, the block with the greater mass will be more dense. If the blocks have the same mass, the block with the smaller volume with have the greater density. If a block has both a greater mass and smaller volume than the other block, then it will be more dense than the other block. In the situation where one block has a greater mass and larger volume than the other block, it is not possible to determine the relative densities of the blocks. In the first image, the green block on the left has both a larger volume and a greater mass than the blue block on the right. Although it is possible that these blocks have the same density, it is not possible to make this determination without knowing the actual volumes and masses of the blocks. Thus, the block that is more dense cannot be determined. In the second image, both blocks have the same volume. The blue block on the right has a greater mass than the green block on the left. Therefore, the blue block on the right is more dense. In the third image, the green block on the left has a smaller volume and greater mass than the blue block on the right. Therefore, the green block on the left is more dense.

Arrange the four liquids in the order they would position themselves in a test tube based on their densities.

Top of test tube acetone, d= 0.70 g/mL turpentine, d= 0.87 g/mL glycerin, d= 1.26 g/mL mercury, d= 13.29 g/mL Bottom of test tube

If you drop a block of metal and a cork into water, the metal will sink but the cork will float. Arrange the relative densities of these substances from the most dense to the least dense. A beaker of water. A cork floats on the surface of the water. A block of metal sits at the bottom of the beaker.

metal water cork Density is mass per unit volume. Because the metal block sinks, this volume of metal has a greater mass than an equal volume of water. Because the cork floats, this volume of cork has a lesser mass than an equal volume of water. Objects sink if they are more dense than water and objects float if they are less dense than water. Therefore, the metal is more dense than water and the cork is less dense than water.

Which of these mixtures are heterogeneous?

oil and water granite (a type of rock with multicolor spots) A homogeneous mixture is a physical combination of two or more subtances that has a uniform composition throughout. A heterogeneous mixture is a physical combination of two or more substances that has a nonuniform composition. When oil and water are mixed in a cup, two distinct layers form. The liquid at the top of the cup will look distinctly different than the liquid at the bottom of the cup. Therefore a mixture of oil and water is a heterogeneous mixture. When salt and water are mixed, the salt completely dissolves in the water to form a solution. The liquid in any area of the cup will look exactly the same as the liquid in any other area of the cup. Therefore a mixture of salt and water is a homogeneous mixture. Brass, an alloy of copper and zinc, is a mixture of metals that looks completely uniform to the human eye because the two components are well mixed down to the molecular level. Brass is therefore a homogeneous mixture. The different minerals that make up granite are visible as different colored spots in the rock. Granite is therefore an example of a heterogeneous mixture.

To what decimal place should each answer be rounded? How many significant figures does the rounded answer have? A. 9 cm+2.8 cm=11.8 cm(unrounded) After rounding, the number should be reported to the; Thus, the number has: B. 0.135 atm+0.6 atm=0.735 atm(unrounded) After rounding, the number should be reported to the; Thus, the number has:

ones place; 2 significant figures tenths place; 1 significant figure For addition and subtraction operations, the least precise number limits the decimal place to which you should report the answer. A.) 2.8 is precise to the tenths place. 9 is only precise to the ones place. Thus, the answer must be rounded to the ones place. 11.8 ≈ 12, which has two significant figures. B.) 0.135 is precise to the thousandths place. 0.6 is only precise to the tenths place. Thus, the answer must be rounded to the tenths place. 0.735 ≈ 0.7, which has one significant figure.

Four marbles are made of different metals. Each marble has the same mass, but a different volume. The density of each metal is given in the table. Metal Density (g/mL) titanium 4.51 lead 11.3 iridium 22.5 tin 7.26 Place the marbles in order from largest to smallest

titanium marble tin marble lead marble iridium marble Density is the mass of a substance per unit of volume. density=mass/volume The density of an object is inversely related to its volume. When comparing two objects that have the same mass but different densities, the less dense object has the greater volume. Each marble has the same mass. Therefore, the largest marble is made from the least dense material, titanium. In order of decreasing volume, the titanium marble is followed by the tin marble, the lead marble, and finally, the iridium marble.