CHEM Session 1
A large piece of jewelry has a mass of 132.6 g. A graduated cylinder initially contains 48.6 mL water. When the jewelry is submerged in the graduated cylinder, the total volume increases to 61.2 mL. (a) Determine the density of this piece of jewelry. (b) Assuming that the jewelry is made from only one substance, what substance is it likely to be? Explain.
(a) 10.5 g/cm3 (b) silver, because silver has density = 10.5 g/cm3(Table 1.4)
1.77. Make the conversion indicated in each of the following: (a) the length of a soccer field, 120 m (three significant figures), to feet (b) the height of Mt. Kilimanjaro, at 19,565 ft the highest mountain in Africa, to kilometers (c) the area of an 8.5 × 11-inch sheet of paper in cm2 (d) the displacement volume of an automobile engine, 161 in.3, to liters (e) the estimated mass of the atmosphere, 5.6 × 1015 tons, to kilograms (f) the mass of a bushel of rye, 32.0 lb, to kilograms (g) the mass of a 5.00-grain aspirin tablet to milligrams (1 grain = 0.00229 oz)
(a) 120 m 1.0936 yd ×1 m3 ft 1 yd × = 394 ft (b) 19,565 ft 12 in. ×1 ft2.54 cm ×1 in.1 m ×100 cm1 km 1000 m × = 5.9634 km 8.5 in. 11 in. = 93.5 in. ×( )2 (c) 2 2.54 cm ×( )2 1 in. ⎛ ⎞ ⎜ ⎟ × 2 = 6.0 10 × 3 161 in. 2.54 cm 1 L (d) 3 ×1 in. ⎝ ⎠ = 2.64 L 1000 cm 3 (e) 15 5.6 10 short tons × 907.185 kg/ short tons ×18 = 5.1 × 10 kg (f) 32.0 lb 0.45359 kg 1 lb × = 14.5 kg (g) 5.00 grain 0.00229 oz ×1 grain28.349 g 1 oz × = 0.324 g 0.411 g 1000 mg 1 g × = 324 mg
1.53. Perform the following calculations and report each answer with the correct number of significant figures. (a) 628 × 342 (b) (5.63 × 102) × (7.4 × 103) (c) 28.0 13.483 (d) 8119 × 0.000023 (e) 14.98 + 27,340 + 84.7593 (f) 42.7 + 0.259
(a) 2.15 × 105; (b) 4.2 × 106; (c) 2.08; (d) 0.19; (e) 27,440; (f) 43.0
1.91. Calculate these volumes. (a) What is the volume of 25 g iodine, density = 4.93 g/cm3? (b) What is the volume of 3.28 g gaseous hydrogen, density = 0.089 g/L?
(a) 5.1 mL; (b) 37 L
1.45. Express each of the following numbers in exponential notation with correct significant figures: (a) 704 (b) 0.03344 (c) 547.9 (d) 22086 (e) 1000.00 (f) 0.0000000651 (g) 0.007157
(a) 7.04 × 10^2 (b) 3.344 × 10^-2 (c) 5.479 × 10^ (d) 2.2086 × 10^4 (e) 1.00000 × 10^3 (f) 6.51 × 10^-8 (g) 7.157 × 10^-3
1.89. Calculate these masses. (a) What is the mass of 6.00 cm3of mercury, density = 13.5939 g/cm3? (b) What is the mass of 25.0 mL octane, density = 0.702 g/cm3?
(a) 81.6 g; (b) 17.6 g
Microscopic, Macroscopic, and Symbolic Domains
(a) Moisture in the air, icebergs, and the ocean represent water in the macroscopic domain. (b) At the molecular level (microscopic domain), gas molecules are far apart and disorganized, solid water molecules are close together and organized, and liquid molecules are close together and disorganized. (c) The formula H2O symbolizes water, and (g), (s), and (l) symbolize its phases. Note that clouds are actually comprised of either very small liquid water droplets or solid water crystals; gaseous water in our atmosphere is not visible to the naked eye, although it may be sensed as humidity.
1.17. Classify each of the following as an element, a compound, or a mixture: (a) iron (b) oxygen (c) mercury oxide (d) pancake syrup (e) carbon dioxide (f) a substance composed of molecules each of which contains one hydrogen atom and one chlorine atom (g) baking soda (h) baking powder
(a) element; (b) element; (c) compound; (d) mixture; (e) compound; (f) compound; (g) compound; (h) mixture
1.56. Classify the following sets of measurements as accurate, precise, both, or neither. (a) Checking for consistency in the weight of chocolate chip cookies: 17.27 g, 13.05 g, 19.46 g, 16.92 g (b) Testing the volume of a batch of 25-mL pipettes: 27.02 mL, 26.99 mL, 26.97 mL, 27.01 mL (c) Determining the purity of gold: 99.9999%, 99.9998%, 99.9998%, 99.9999%
(a) neither; (b) precise but not accurate; (c) both accurate and precise
1.27. Classify each of the following changes as physical or chemical: (a) condensation of steam (b) burning of gasoline (c) souring of milk (d) dissolving of sugar in water (e) melting of gold
(a) physical; (b) chemical; (c) chemical; (d) physical; (e) physical
1.49. How many significant figures are contained in each of the following measurements? (a) 53 cm (b) 2.05 × 108 m (c) 86,002 J (d) 9.740 × 104 m/s (e) 10.0613 m3 (f) 0.17 g/mL (g) 0.88400 s
(a) two; (b) three; (c) five; (d) four; (e) six; (f) two; (g) five
Liquid
*the state of matter that has a definite volume but not a definite shape *flows and takes the shape of its container
What is the answer to 7.884 x 0.227 ÷ 1.9, reported to the correct number of significant figures? 0.9419 0.942 0.94 0.9
0.94
The Categories of Matter
1. Pure substance (elements and compounds) 2. Mixture
When multiplying or dividing measurements 1. The number of significant figures in the answer will equal the fewest significant figures in a number in the calculation 2. The number of significant figures in the answer will equal the greatest significant figures in a number in the calculation 3. The number of decimal places in the answer will equal the fewest decimal places in a number in the calculation 4. The number of decimal places in the answer will equal the greatest decimal places in a number in the calculation
1. The number of significant figures in the answer will equal the fewest significant figures in a number in the calculation
What is the answer to 100.1 + 8.999 - 0.01, reported with the correct number of significant figures? 109.089 109.09 109.1 109
109.1
Which of the following is a physical change? 1. A garden tool rusting 2. Condensation forming on a window 3. Toast burning 4. Combustion of gasoline in a car
2. Condensation forming on a window
A liquid 1. Has fixed shape and volume 2. Takes shape of a container and forms a horizontal upper surface 3. Expands to completely fill a container 4. Is rigid and has a definite shape
2. Takes shape of a container and forms a horizontal upper surface
A Class-A 10 mL pipette is supposed to dispense 10.00 mL of water. A lab technician makes three measurements of the volume that the pipette actually dispenses, and obtains volumes of 10.21 mL, 9.73 mL, and 10.14 mL. The pipette is 1. Accurate, but not precise 2. Precise, but not accurate 3. Accurate and precise 4. Neither accurate or precise
4. Neither accurate or precise
How many milligrams are in 405 kg? 4.05 x 10^8 mg 4.05 x 10^5 mg 4.05 x 10^-3 mg 4.05 x 10^-4 mg
4.05 x 10^8 mg
The density of copper is 8.96 g/cm3. What is the volume in cm3 of 1.35 pounds of copper? 68.3 cm3 5.49 x 10^3 cm3 3.32 x 10^-4 cm3 2.67 x 10^-2 cm3
68.3 cm3
Weight
A measure of the gravitational force exerted on an object.
Molecule
A molecule consists of two or more atoms joined by strong forces called chemical bonds.
The Scientific Method
A series of steps followed to solve problems including collecting data, formulating a hypothesis, testing the hypothesis, and stating conclusions. *leads from question and observation to law or hypothesis to theory, combined with experimental verification of the hypothesis and any necessary modification of the theory!! 1. Observation (about reality)- gathering data 2. Ask a question- why??? 3. Testable explanation (hypothesis) 4. Design an experiment (procedure of steps) 5. Prediction 6. Test, analyze, and conclude!! 7. Refine and interate
Gas
A state of matter with no definite shape or volume *Takes both the shape and volume of its container
Significant Digits
All of the digits in a measurement, including the uncertain last digit!!
Homogenous Mixture
Also called a SOLUTION uniform composition and appears visually the same throughout. Sport drink, air, maple syrup, gasoline, solution of salt in water
Matter
Anything that has mass and takes up space (volume) Solid, liquid, and gas
Atom
Atom is the smallest particle of an element that has the properties of that element and can enter into a chemical combination. It is rare to find collections of individual atoms. Only a few elements, such as the gases helium, neon, and argon, consist of a collection of individual atoms that move about independently of one another. Other elements, such as the gases hydrogen, nitrogen, oxygen, and chlorine, are composed of units that consist of pairs of atoms
Physical Property
Characteristic of matter that is not associated with a change in its chemical composition. Density, color, hardness, melting/boiling points, electrical conductivity. Some physical properties, such as density and color, may be observed without changing the physical state of the matter. Other physical properties, such as the melting temperature of iron or the freezing temperature of water, can only be observed as matter undergoes a physical change.
A pure substance that can be broken down into simpler substances by chemical changes is a/an Element Compound Mixture Solution
Compound
Calculation of Density
D=m/v
Pure Substance
Has a constant composition; all specimens of a pure substance have exactly the same makeup and properties. Elements Compounds
Temperature SI base unit
Kelvin (K) Celsius
Law of conservation of matter
Matter is not created nor destroyed in any chemical or physical change
Volume
Measure of the amount of space occupied by an object. cubic meter (m3) liter (L) cubic centimeter (cm3) mL
Alloys
Metals are combined to form alloys Ex: copper and tin combined to form tin
Compounds
Pure substance that CAN be broken down by chemical changes. *This breakdown can create either elements or other compounds. Properties of combined elements are different than those in free or uncombined state.
rounding numbers
Round the Numbers in picture
Time SI base unit
Seconds (s)
Law
Summarize experimental observations and describe or predict some facet of the natural world. *An OBSERVATION of the natural world A detailed description of how something happens Ex: increased heat, increased pressure
Hypothesis
Tentative explanation of observations that acts as a guide for gathering and checking information. *A hypothesis is tested by experimentation, calculation, and/or comparison with the experiments of others and then refined as needed.
Significant Figures and Measurement
The bottom of the meniscus in this case clearly lies between the 21 and 22 markings, meaning the liquid volume is certainly greater than 21 mL but less than 22 mL. The meniscus appears to be a bit closer to the 22-mL mark than to the 21-mL mark, and so a reasonable estimate of the liquid's volume would be 21.6 mL. In the number 21.6, then, the digits 2 and 1 are certain, but the 6 is an estimate. In general, numerical scales such as the one on this graduated cylinder will permit measurements to one-tenth of the smallest scale division. The scale in this case has 1-mL divisions, and so volumes may be measured to the nearest 0.1 mL. This concept holds true for all measurements, even if you do not actively make an estimate. If you place a quarter on a standard electronic balance, you may obtain a reading of 6.72 g. The digits 6 and 7 are certain, and the 2 indicates that the mass of the quarter is likely between 6.71 and 6.73 grams. The quarter weighs about 6.72 grams, with a nominal uncertainty in the measurement of ± 0.01 gram. If the coin is weighed on a more sensitive balance, the mass might be 6.723 g. This means its mass lies between 6.722 and 6.724 grams, an uncertainty of 0.001 gram.
Chemical Property
The change of one type of matter into another type (or the inability to change) flammability, toxicity, acidity, and many other types of reactivity. Iron, for example, combines with oxygen in the presence of water to form rust!!
Solid
The state of matter that has definite shape and volume
Mass vs. Weight
The weight of an object will change as the force of gravity changes but the mass does not change.
A comprehensive, testable explanation that explains a large body of experimental data is a/an? Hypothesis Theory Law Model
Theory!!
Physical Change
a change in the state or properties of matter without any accompanying change in the chemical identities of the substances contained in the matter. wax melts when sugar dissolves in coffee when steam condenses into liquid water Other examples of physical changes include magnetizing and demagnetizing metals (as is done with common antitheft security tags) and grinding solids into powders (which can sometimes yield noticeable changes in color). In each of these examples, there is a change in the physical state, form, or properties of the substance, but no change in its chemical composition.
Water Displacement Method
a method that involves putting an object into water and carefully recording how much the water level rises
Mixture
a mixture is composed of two or more types of matter that can be present in varying amounts and can be separated by physical changes. -heterogenous mixture -homogeneous mixture
Extensive Property (physical)
a property that depends on the amount of matter in a sample DOES change with amount!!! Ex: Mass an volume (a gallon of milk has a larger mass than a cup of milk) Value of an extensive property is directly proportional to the amount of matter in question
dimensional analysis
a technique of problem-solving that uses the units that are part of a measurement to help solve the problem units of quantities must be subjected to the same mathematical operations as their associated numbers uses unit conversion factors
Accuracy vs. Precision
accuracy: how close experimental value is to accepted value; precision: how closely measured values agree with each other
What digits are significant and which ones are not??
all nonzero digits are significant!! Start by counting the FIRST non-zero digit on the left *The leading zeros in this example are not significant. We could use exponential notation and express the number as 8.32407 ×× 10−3; then the number 8.32407 contains all of the significant figures, and 10−3 locates the decimal point.
Plasma
gaseous state of matter that contains appreciable numbers of electrically charged particles *In addition to stars, plasmas are found in some other high-temperature environments (both natural and man-made), such as lightning strikes, certain television screens, and specialized analytical instruments used to detect trace amounts of metals.
Mass SI base unit
kilogram (kg)
sig figs in addition and subtraction
least number of decimal places -round the result to the same number of decimal places as the number with the least number of decimal places
sig figs in multiplication and division
least number of sig figs - round the result to the same number of digits as the number with the least number of significant figures
Density
mass/volume *ratio of the mass of a sample of the substance to its volume. (kg/m3), (g/m3)
Length SI base unit
meter (m)
Heterogenous Mixture
mixture with a composition that varies from point to point. Italian dressing, chocolate chip cookie, granite
Exact Number
number derived by counting or by definition Ex: counting eggs in a carton, one can determine exactly how many eggs the carton contains. numbers of defined quantities are also exact. By definition, 1 foot is exactly 12 inches, 1 inch is exactly 2.54 centimeters, and 1 gram is exactly 0.001 kilogram.
Chemical Change
produces one or more types of matter that differ from the matter present before the change. formation of rust is a chemical change because rust is a different kind of matter than the iron, oxygen, and water present before the rust formed.
Intensive Property (physical)
property of a sample of matter does not depend on the amount of matter present DOES NOT change with amount!!!! Ex: temperature Density is intensive!
Elements
pure substances that cannot be broken down into simpler substances by ordinary chemical means!!
Measuring volume of liquid in a graduated cylinder Where do you read the graduated cylinder??
reading at the bottom of the meniscus, the lowest point on the curved surface of the liquid.
Microscopic Domain of Chemistry
realm of things that are much too small to be sensed directly. Cells, molecules, atoms, ions, electrons, protons, neutrons, chemical bonds.
symbolic domain of chemistry
specialized language used to represent components of the macroscopic and microscopic domains, such as chemical symbols, chemical formulas, chemical equations, graphs, drawings, and calculations.
units
standards of comparison for measurements
Mass
the amount of matter in an object
Macroscopic Domain of Chemistry
the realm of everyday things that are large enough to be sensed directly by human sight or touch. * Everyday and laboratory chemistry: density, solubility, and flammability.
What information does measurement provide?
the size or magnitude of the measurement (a number); a standard of comparison for the measurement (a unit); and an indication of the uncertainty of the measurement.
International System of Units
the system of units (SI) used by scientists to measure the properties of matter
Celsius
unit of temperature; water freezes at 0 °C and boils at 100 °C on this scale
Theory
well-substantiated, comprehensive, testable explanation of a particular aspect of nature. *TESTABLE explanation of the natural world. EXPERIMENTATION A well-substantiated explanation acquired through the scientific method and repeatedly tested and confirmed through observation and experimentation. Ex: after much research and experimentation, can explain WHY increased heat causes increased pressure.