Chem Lab Exam #1

Front 1

Purpose/ Procedure of Relationships and predicting values

Back 1

Purpose: Determine the value of an unknown by looking at another graph and using the equation given.

Procedure: Create linreg graph from the given X and Y values (change x^e to get it as straight as possible), find the equation and plug in given numbers to find M (slope)

Front 2

Purpose/ Procedure of Moisture content of popcorn

Back 2

Purpose: to determine the % water in a kernel of popcorn

Procedure: weigh before, pop, weigh after = the % water that left. Compare with other groups. Preform a Q-test, find the mean, median and mode, standard dev, %RSD, and the StDEV of the mean. Conduct T-test between 2 groups and the optimal %.

Front 3

Purpose/ Procedure of Density and % sugar of beverages

Back 3

Purpose: to determine the density and % sugar in an unknown beverage

Procedure: Make standard solutions, make a graph (calibration curve), determine sugar content in unknown by using the y=mx+b (interpolation), before that you have to get the average density

Front 4

Purpose/ Procedure of empirical formula lab

Back 4

Purpose: find the empirical formula using the law of multiple proportions

Purpose: get CuClH2O, burn the Cl out, dry out the sample and get the amount of water lost. Convert mass copper, chlorine, and water to moles. Find empirical formula by dividing the moles of substance by the smallest moles

Front 5

how to find m and x in y=mx+b

Back 5

m= y/x^?

x?= what ever the exponent was to make the graph linear

x=y-b/m

Front 6

how to find the % water

Back 6

mass water= mass of the kernel before-after (convert to %)

% Water= Mass water/ Mass un-popped x100

Front 7

Q-test

Back 7

(|suspected value - its nearest neighbor|)/Range

Front 8

standard deviation

Back 8

(all of the means added^2/ number of trials -1)^1/2

Front 9

%RSD

Back 9

standard deviation/ mean x100

Front 10

Standard deviation of the mean

Back 10

StDev/ square root of the number of trials

Front 11

t-test

Back 11

|xm1 - xm2| > t*(sm12 + sm22)1⁄2

Front 12

w/w% sugar

Back 12

mass solute/ mass solution x100

Front 13

density of sugar

Back 13

mass solution/ volume of the solution

Front 14

% sugar

Back 14

y=mx+b equation

y=density and m,x,b are found in the equation from the linreg graph

Front 15

sig figs for different flasks

Back 15

25mL graduated cylinder= 3 sig figs because calibrations every mL

25mL erlenmeyer flask and beaker= 2 sig figs because calibrations every 5mL

Front 16

Experiment 3 introduces the concept of density. Specifically, students will be finding the density of a liquid. Students will be making a ___________ curve of known _________ concentration. This curve will help to determine the sugar content of an “unknown” commercial beverage. Separate your answers with a comma.

Back 16

calibration, sugar

Front 17

A substance can be characterized by physical properties such as mass, volume, color, and density. Density is an example of an intensive property, meaning it is ______________ on the amount of substance present. An extensive property like volume is ___________ on the amount of substance present. Separate your answer with a comma.

Back 17

independent, dependent

Front 18

Students will be measuring the density of aqueous solutions. This means that the solvent that makes up the solution is __________.

Back 18

water

Front 19

f hydrochloric acid (HCl) is sold as a 28% solution, that means that the reagent contains 28 grams of HCl per 100 grams of the solution. What is the mass of the solvent in this example? ____________ grams

Back 19

72

Front 20

To determine the density of a substance, it’s mass and volume must be measured. Which piece of glassware will be used to measure the volume of the solution? _________________

Back 20

volumetric flask

Front 21

Unlike a solid, a liquid cannot be weighed on a balance unless it’s contained. The standard method for obtaining the mass of a liquid is described in the manual and it is called _____________ ______ _____________.

Back 21

weighing by difference

Front 22

If a 10 mL volumetric flask is used to measure its maximum volume, express the measurement in the correct number of significant figures. ________ mL

Back 22

10.00

Front 23

One of the objectives of Experiment #4 is to use reaction stoichiometry to determine the number of moles of each of the components of a ______________ binary salt (CuxCly•zH2O).

Back 23

hydrated

Front 24

3Cu2+ (aq) + 2Al (s) → 3Cu (s) + 2A13+ (aq)

The strongest reducing agent in this reaction is:

Back 24

Al

Front 25

When the unknown copper chloride hydrate is heated, its color changes to _______?

Back 25

brown

Front 26

What term is used to describe the liquid accumulated in the filter flask during vacuum filtration?

Back 26

filtrate

Front 27

Using a solution of known concentration to determine the concentration of another solution through a monitored reaction of known stoichiometry that goes to completion is called ________________.

Back 27

titration

Front 28

In an acid-base titration, the ______________________ ______________ occurs when the number of moles of acid is stoichiometrically equal to the number of moles of base added to neutralize the acid.

Back 28

equivalence point

Front 29

Any titration requires that the reaction be monitored to determine when the equivalence point has been reached. For acid-base titrations, the most common methods rely on ____________________.

Back 29

measuring the pH

Front 30

What device is used to both deliver and measure the amount of sodium hydroxide (NaOH) to the citric acid solution?

Back 30

buret

Front 31

The oxidation number of an atom in its elemental form is ________________.

Back 31

0

Front 32

Evidence of a single displacement reaction

Back 32

olor change in the solution and/or deposition of the displaced metal on the surface of the reactive metal.

Front 33

accuracy

Back 33

the degree of agreement between a measured value of a quantity and the true value of the quantity

Front 34

precision

Back 34

the degree of agreement among several measured values of the same quantity