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Qualitative

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noting observations such as color, color changes, hardness, whether heat is liberated or absorbed, and odor.

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Quantitative

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noting the amount of a measurable change in mass, volume, or temperature, for example, fro which the qualitative data are already known.

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Four objectives in the laboratory

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1. To develop the skills necessary to obtain and evaluate a reliable original result. 2. To record your results for future use. 3. To be able to draw conclusions regarding you results (with the aid of some coaching and reading in the beginning.) 4. To learn to communicate your results critically and knowledgeably.

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Safety Rule 1

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Wear approved eye protection (including splash guards) at all times while in the laboratory. -must include shatterproof lenses and side shields. -use fountain before the material runs behind your eyeglasses and into your eyes. There is a "panic bar" for easy activation.

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Safety rule 2

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Wear shoes at all times

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Safety rule 3

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Eating, drinking, and smoking are strictly prohibited in the laboratory at all times.

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Safety rule 4

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Know where to find and how to use all safety and first-aid equipment.

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Safety Rule 5

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Consider all chemicals to be hazardous unless you are instructed otherwise. Dispose of chemicals as directed by your instructor.

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Safety rule 6

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If chemicals come into contact with your skin or eyes, wash immediately with copious amounts of water and then consult your laboratory instructor

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Safety rule 7

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Never taste anything. Never directly smell the source of any vapor or gas.

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Safety rule 8

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Perform in the fume exhaust hood any reactions involving skin-irritating or dangerous chemicals, or unpleasant odors.

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Exhaust hoods

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-have fans to exhaust fumes out of the hood and away from the user. -used when studying noxious, hazardous and flammable materials. -shatterproof glass window used as a shield to protect you from minor explosions -toxic fumes are stored in the hood.

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safety rule 9

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never point a test tube that you are heating at yourself or your neighbor. It may erupt like a geyser.

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safety rule 10

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Do not perform any unauthorized experiments.

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safety rule 11

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clean up all broken glassware immediately

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safety rule 12

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always pour acids into water, not water into acid, becuase the heat of solution will cause the water to boil and the acid to spatter. "Do as you oughter, pour acid into water"

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safety rule 13

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avoid rubbing your eyes unless you know that your hands are clean.

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safety rule 14

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when inserting glass tubing or thermometers into stoppers. lubricate the tubing and the hole in the stopper with glycerol or water. -wrap the rod in a towel -grasp it as close to the end being inserted as possible. -slide the glass into the rubber stopper with a twisting motion. -remove the excess lubricant -keep you hands as close together to reduce leverage.

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safety rule 15

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always place the ring stand as far back on the laboratory bench as comfortable, with long edges or the base perpendicular to the front of the bench.

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safety rule 16

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notify the instructor immediately in case of an accident.

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safety rule 17

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many common reagants- alcohol, acetone- are highly flammable. So not use them anywhere near open flames.

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safety rule 18

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observe all special precautions mentioned in experiments.

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safety rule 19

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learn the location and operation of fire protection devices

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carbon dioxide fire exinguishers

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-available in lab -pull the metal safety ring from the handle and depress the handle. -Direct at the base of the flames. -turn in at stockroom to be refilled -evacuate laboratory if it does not work.

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Clothing

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bulky or loose sleeves should not be worn in the laboratory.

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emergency water shower

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-pull the metal ring -dumps 40-50 gallons of water -cannot be shut off once the metal ring has been pulled

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Basic instructions for lab work

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1. read assignment before coming to the lab 2. work independently 3. record results on notebook or report sheet 4. work conscientiously to avoid accidents 5. dispose excess reagents as instructed 6. hold reagent-bottle stoppers in your hand 7. leave reagent bottles on the shelf where you found them 8. use only the amount of reagent called for; avoid excesses. 9. Use distilled water. 10. keep your area clean. 11. do not borrow apparatus from other desks. 12. do not place chemicals directly on the balance when weighing. 13. do not weigh hot or warm objects. should be room temperature. 14. Do not put hot objects on the desktop. place them on a wire gauze or heat-resistant pad.

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SI units

answer

International system of units

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Temperature formula

answer

5/9 (F-32) or F= 9/5 C +32

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Meter Rule

answer

39.37 inches in length. divided into centimeters (1cm= 0.01 m; 1m=100 cm) and millimeters (1mm= 0.001 m; 1m= 1000mm) ***1 inch=2.54 cm*** one side is ruled in inches and other side ruled in centimeters accuracy=0.1 cm (1 mm)

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Graduated Cylinders

answer

tall, cylindrical vessels used measure volume by measuring the height of column of liquid have a uniform diameter along its height. Liter is divided into milliliters 1mL=0.001 L and 1L= 1000mL. 100 mL graduated cylinder scribed in milliliters

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meniscus

answer

curved surface of water in a tube

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Thermometers

answer

principle that liquids expands when they are heated use mercury or colored alcohol so that a uniform diameter capillary tube surmounts a liquid reservoir freezing point (0 C, 32 F) boiling point (100 C, 212 F) 1 atm of pressure (1 atm= 760 mm Hg) check the accuracy of your thermometer compare with true temperatures

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degrees

answer

uniform divisions there are 100 degree difference between freezing and boiling points on the celcius scale and 180 degrees between the points on the fahrenheit scale.

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Pipets

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glass vessels constructed and calibrated to deliver a precisely known volume of liquid at a given temperature. Always use a rupper bulb to fill a pipet. Never use your mouth A TD pipet should not be blown empty 10 mL

question

Proper care of the balance

answer

1. Do not drop an object on the pan 2. center the object on the pan 3. do not place chemicals directly on the pan; use a beaker, a watch glass, a weighing bottle, or weighing paper. 4. do not weigh hot or warm objects; objects must be at room temperature. 5. return all weights to the zero position after weighing 6. Clean up any chemical spills in the balance area. 7. inform your instructor if the balance is not operating correctly ; do not attempt to repair it yourself.

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Density

answer

liquids- g/mL gases- g/L solids- g/cm3

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Precision

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a measure of the reproducibility of a given set of results

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arithmetic mean (average)

answer

the "best" value

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average deviation

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determine the mean of the measurements, calculate the deviation of each measurement from the mean and averaging deviations (value-mean).

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Properties

answer

characteristics of a substance that enable you to identify it and distinguish it from other substances.

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physical properties

answer

properties that can be observed without altering the composition of the substance melting point, boiling point, solubility, density, viscosity, and refractive index.

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Identification of substances by physical properties

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you will identify a substance whose identity is unknown to you: solubility, density, melting point, and boiling point.

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Solubility

answer

substance in a solvent at a specified temperature is the maximum weight of that substance that dissolves in a given volume of a solvent.

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freezing point

answer

when solid begins to appear in the liquid.

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melting point

answer

when liquid begins to appear in the solid.

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Boiling point

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when bubbles of vapor form in the liquid. depends upon atmospheric pressure.

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normal boiling point

answer

liquid boils at 760 mm Hg

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namograph

answer

a set of scales for connected variables. provides the unknown value at the straight line's intersection find correction necessary to convert the normal boiling point of a substance to its boiling point at any pressure of interest. left scale is normal b.p and right side is correction T(triangle). Draw a line between the two points to get the correction

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Lab 1 topic procedures

answer

a) the meterstick b) graduated cylinder c) the thermometer and its calibration d) using the balance to calibrate your 10 mL pipet e) measuring the density of antifreeze

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Lab 2 topic procedures

answer

a) solubility b) density c) melting point of solid unknown d)boiling point of liquid unknown e) unknown identification

question

room temperature

answer

25 degrees C

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water density

answer

1.00 g/mL

question

what are msds sheets

answer

A Material Safety Data Sheet (MSDS) is a document that gives detailed information about the nature of a chemical, such as physical and chemical properties, health, safety, fire, and environmental hazards of a chemical product. They are designed for: ? workers who may be exposed to hazardous materials.

question

Lab 1 detailed procedures

answer

A) Measure length and width of lab book in both units using meterstick. B) Fill graduated cylinder half full with water. Lowest point on the curve of the meniscus is is volume. Measure to the nearest 0.1 mL. C) Freezing point= 0 C boiling point= depends on atmospheric pressure place 50 mL of ice in 250 mL beaker. Cover ice with distilled water. Wait 15 minutes and the record temperature. Use a thermometer. D) Fill a 250 mL beaker on a wire gauge half full with distilled water. Put burner on maximum heating. receive temperature boiling point= when temperature is constant find true boiling point using b.p correction formula. E) put 40 mL of dH2O in a 150 mL beaker. Record mass of empty 50 mL Erlenmyer (tare) flask to the nearest 0.1 mg. record temperature of water pipet 10 mL of water into flask and weigh the flask with it at 0.1 mg. mass= gross- tare = net F) weigh dry 50 mL flask to nearest 0.1 mg and record mass. Measure flask with 10 mL of antifreeze solution. repeat 2 more times (for precision). Calculate density calculate mean, density, and average deviation from the mean.

question

Metric system prefixes

answer

femto- (f) 10^-15 pico- (p) 10^-12 nano- (n) 10-9 micro- (u) 10^-6 milli- (m) 10^-3 centi- (c) 10^-2 deci- (d) 10^-1 kilo- (k) 10^3 mega- (M) 10^6 giga- (G) 10^9

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Density

answer

mass/ unit volume

question

Length

answer

meter (m) meter and centimeters

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Volume

answer

cubic meter (m^3) liter and milliliter

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Mass

answer

kilogram gram and milligram

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Energy

answer

Joule (J) calorie (cal)

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Temperature

answer

kelvin degree celsius

question

How to calculate mean value and the average deviation from the mean

answer

mean= 10.15 + 10.12 + 10.00 / 3 = 10.09 deviations from the mean: (value- mean) 10.15- 10.09 = 0.06 10.12 - 10.09 = 0.03 10.00 - 10.09 = 0.09 average deviation 0.06+ 0.03 + 0.09 / 3 = 0.06 Value is 10.09 and 0.06 mL

question

what are the basic units of length, mass, volume, and temperatures in the SI system?

answer

Mass, kilogram; temperature, K; volume, m^3 ; length, meter; and energy, joule.

question

what decimal power do the following abbreviations represent: (a) M, (b) k, (c) m, (d) n (e) u

answer

a) 6 b) 3 c)-3 d) -9 e) -6

question

what is the length in milliliters of a crystal of copper sulfate that is 0.250 inch long?

answer

(0.250 in) (2.54 cm/in) (10 mm/ 1 cm) = 6.35 mm

question

conversions: a) 72.3 mg to g b) 6.0 * 10^-10m to mm c) 325 mm to um

answer

a) 0.0723 mg b) 6.0 x 10^-7 mm c) 3.25 x 10^5

question

DNA is 2.5 nm in length. a man is 6 ft tall. How many DNA molecules could be stacked end to end in an average man?

answer

6 ft 12in/ 1 ft 2.54cm/1in 10^-2m/ 1cm 1nm/10^-9 m 1 DNA mol. / 2.5 nm = 7.3 X 10 ^ 8

question

a liquid has a volume of 3.70 liters. What is its volume in mL? In cm^3?

answer

3,700 mL 3,700 cm^3

question

Why should you never weigh a hot object?

answer

convection currents tend to buoy the object and thus lead to an inaccurately low mass. Moreover, hot objects can damage the balance.

question

Why is it necessary to calibrate a thermometer and volumetric glassware?

answer

Thermometers and volumetric glassware are designed to be accurate. But their manufacture is subject to human error, and they should be calibrated.

question

what is precision?

answer

Precision is a measure of the internal consistency of a replicate set of data.

question

what is the density of an object with a mass of 1.663g and a volume of 0.2009 mL?

answer

d=m/v d= 1.663g/ 0.2009 = 8.28 g/mg

question

weighing an object three times gave the following results: 9.2g , 9.1 g, and 9.3g. Find the mean mass and the average deviation from the mean.

answer

mean= 9.3 + 9.1 +9.2 /3 = 9.2 average deviation from mean= 0.1+0.1+0.0 /3 = 0.07

question

normal body temperature is 37.0 C. What is the corresponding fahrenheit temperature?

answer

(9/5 * 37) +32 = 98.6 F

question

What is the mass in kilograms of 750 mL of a substance that has a density of 0.930 g/mL?

answer

d=m/v m=dv= (0.930 g/mL) (750 mL) = 698g 698 g= 0.698 kg

question

List 5 physical properties

answer

solubility, color, melting point, boiling point, and density.

question

a 1.22 g sample of an unknown has a volume of 1.73 cm^3. what is the density of the unknown?

answer

D= m/v d= 1.22 g / 1.73 cm^3 =0.71 g/cm^3

question

Are the substances lauric acid and stearic acid solids or liquids at room temperature?

answer

room temperature= 20 C SOLID

question

could you determine the density of zinc chloride using water? why or why not?

answer

No because it is soluble in water

question

What would be the boiling point of hexane at 670 mm hg?

answer

normal boiling = 69 C normal b.p. - correction = observed b.p. 69-5= 64C

question

Why do you calibrate thermometers and pipets?

answer

humans make mistakes when it comes to mass-produced items.

question

Is toluene miscible with water? With ethyl alcohol?

answer

No with water but with ethyl alcohol.

question

when water and bromoform are mixed, two layers form. Is the bottom layer water or bromoform?

answer

Bromoform

question

What solvent would you use to determine the density of zinc chloride?

answer

cyclohexane

question

The density of a solid with a melting point of 42 to 44 C was determined to be 0.87 +- 0.02 g/mL. What is the solid?

answer

Lauric acid

question

The density of a liquid whose boiling point is 55 to 57 C was determined to be 0.77 +- 0.05 g/mL. what is the liquid?

answer

Acetone

question

Which has the greater volume- 10g of hexane or 10g of toluene? what is the volume of each?

answer

Density: hexane- 0.66 toluene- 0.87 V= m/d hexane = 10g / 0.66 g/mL = 15 mL Toluene= 10g/ 0.87 g/mL = 11.49 mL = 11 mL HEXANE HAS A GREATER VOLUME

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