Studied by 35 People

5.0(3)

Get a hint

hint

Tags & Description

New cards260

Still learning0

Almost done0

Mastered0

260 Terms

New cards

linear regression

a method used to calculate the "best fit" line that describes the mathematical relationship between two experimental variables that have a linear relationship

New cards

New cards

independent variable

the variable that one typically has control over and is manipulated; plotted on the x-axis

New cards

New cards

dependent variable

the variable that is measured during the experiment; plotted on the y-axis

New cards

New cards

a, b, c

Select all that are true about the "best fit" line with real data. a.) It may not go through all the data points. b.) It does not have to go through the origin. c.) Every data point has some experimental error associated with it.

New cards

New cards

the data they were derived from

The numbers in a linear regression cannot have more significant digits than...?

New cards

New cards

0.990

The correlation of all linear graphs should be greater than what value?

New cards

New cards

calibration curve

a graph that can be used to determine the concentration of an unknown sample of a compound for which you have measured an absorbance

New cards

New cards

known sample

The absorbance of the unknown sample should be within the range of the absorbance measurements of the ...?

New cards

New cards

interpolation

a method that involves solving for an unknown "x" value

New cards

New cards

reduce; oxidized

A more active metal will replace and ... a less active metal during a chemical reaction. The more active metal itself will become ...

New cards

New cards

scientific hypothesis

a reasoned and testable proposal predicting the causal relationship among multiple observations

New cards

New cards

measurements

form the basis of all science; critical to the development and testing of a scientific hypothesis

New cards

New cards

1.) The measuring device 2.) The individual performing the measurement.

Measurements are always accompanied by some level of uncertainty that is a function of what two things?

New cards

New cards

systematic errors

errors that are all approximately of the same magnitude and direction from the true value; can be minimized by well-designed experimental procedures, proper calibration, and maintenance of instrumentation

New cards

New cards

random errors

occur in large part because of of interpretations of measurement readings by experimenters, by random fluctuations in an experimental method, or limits of instrumentation; can be reduced by careful laboratory technique or observation

New cards

New cards

the same as the MEASUREMENT with the smallest amount of sigfigs

If a measurement is multiplied or divided, the number of significant figures will be ?

New cards

New cards

the same as the smallest number of DECIMAL PLACES in a value

If a measurement is added or subtracted, the number of significant figures will be ?

New cards

New cards

infinite

Exact numbers have an ... amount of sigfigs and should not be factored into determining how many sigfigs a calculation should have.

New cards

New cards

more

You should always carry ... significant figures through a calculation than you will need at the end.

New cards

New cards

accuracy

the degree of agreement between a measured value of a quantity and the "true" value of that quantity. (arrows hitting the bullseye)

New cards

New cards

precision

the degree of agreement among several measured values of the same quantity (arrows hitting the same spot, even if it's not the bullseye)

New cards

New cards

accuracy

Systematic errors affect the ... of the measurement.

New cards

New cards

precision

Random errors affect the ... of the measurement.

New cards

New cards

mistakes/determinate errors

accidents that result in a poor measurement; usually only affect one value in a series of repeated measurements of the same quantity

New cards

New cards

central value

the value about which the individual measured values tend to cluster

New cards

New cards

mean

the sum of data points divided by the number of data points (average)

New cards

New cards

median

the central member of a series of data points, arranged in order of magnitude; especially useful when suspecting an outlier

New cards

New cards

mode

the value that occurs most frequently in a data set

New cards

New cards

standard deviation

the most common way to express the precision of a series of measurements; the difference between the mean and the measured data point

New cards

New cards

absolute deviation

the absolute values of the difference between the mean and the data point; absolute value of standard deviations

New cards

New cards

range

the difference between the biggest and the smallest data point; another measurement of absolute precision

New cards

New cards

percent relative standard deviation

a measure of the precision of the individual data points relative to the mean of the data, expressed as a percentage

New cards

New cards

standard deviation of the mean

another measure of precision; estimates the precision of the mean of a group of n independent measurements of the same quantity; standard deviation/root of n

New cards

New cards

systematic error

As the number of individual measurements increases, what becomes the dominant source of error?

New cards

New cards

Q-test

the test that should be applied in cases of 3 to 10 repeat measurements where it appears that one data point is an outlier; can only reject one data point from a set

New cards

New cards

discarded

If the calculated Q value is greater than the critical value, the suspect value should be ....

New cards

New cards

on the high or low end of the range of data

During a Q test, only data points where can possibly discarded?

New cards

New cards

the point that is farther from its nearest neighbor

Which data point on the end of the range of values should be considered for possible removal during a Q test?

New cards

New cards

significance tests

tests that allow an experimenter to compare a measured value to a "true" or accepted value OR to compare two independently measured values of the same quantity to each other

New cards

New cards

n-1

degrees of freedom for a T test for comparison to an accepted value, and for a Q test

New cards

New cards

statistically different

If the absolute value of the difference between the accepted value and the mean is greater than t*sm, the two values are ....

New cards

New cards

statistically different

If a confidence interval does not include the value, then it is ....

New cards

New cards

2n-2

degrees of freedom for comparison of two independent measurements of the same quantity

New cards

New cards

n1+n2-2

degrees of freedom for comparison of two independent measurements of different quantities

New cards

New cards

It uses standard deviation instead of standard deviation of the mean

What is special about the t test for two independent measurements of DIFFERENT quantities?

New cards

New cards

Because popcorn was regarded as a laboratory chemical, and laboratory chemicals cannot be consumed.

Why wasn't it okay to eat the popcorn?

New cards

New cards

True

True or False: The results of individual trials often give a range of values.

New cards

New cards

statistical analysis

provides criteria for rejection of data points and for comparison of numerical quantities

New cards

New cards

to determine the moisture content of popcorn and to use basic statistics to analyze the results

What was the purpose of the popcorn/statistics lab?

New cards

New cards

starch, a variable amount of water, and a hard, moisture-sealed husk

What are kernels primarily composed of?

New cards

New cards

Unpopped kernel

Which popcorn kernel had a higher mass: the popped kernel or the unpopped kernel?

New cards

New cards

It lost mass as water escaped the kernel

Why does the popped kernel have a lower mass than the unpopped kernel?

New cards

New cards

to prevent scorching of the kernels

Why should there be substantial distance from the bottom of the flame to the bottom of the evaporating dish?

New cards

New cards

Mass of unpopped kernel-Mass of popped kernel

Calculation for mass of water (Experiment #2)

New cards

New cards

(mass of water)/(mass of unpopped corn) * 100

Calculation of percent water (Experiment #2)

New cards

New cards

They are considered laboratory chemicals, and cannot be consumed.

Why can the sugar from Experiment #3 not be consumed?

New cards

New cards

Poured down the sink

How can the sugar solutions in Experiment #3 be disposed of?

New cards

New cards

intensive physical properties

independent of the amount of substance; density, color, melting point, boiling point

New cards

New cards

extensive physical properties

dependent on the amount of the substance; volume, mass, and surface area

New cards

New cards

Since they don't change based on amount, they can be used to identify unknown substances

Why are intensive properties such as density important?

New cards

New cards

M/V

Density formula

New cards

New cards

The liquid form of water is more dense than its solid form (ice can float in water)

What is special about water when it comes to density?

New cards

New cards

The other solutes present are present in fairly small amounts compared to sucrose.

Why is the density of a beverage primarily based on sucrose content?

New cards

New cards

weight percent (w/w); volume percent (v/v); weight/volume (w/v)

three common examples of expressing percent composition of a solution

New cards

New cards

(mass solute) / (mass solution) * 100

weight percent (w/w) equation

New cards

New cards

mass of solution - mass of solute

mass of solvent equation

New cards

New cards

standard solutions

solutions where the concentration or amount of solute is known

New cards

New cards

X Axis: Percent Sugar Y Axis: Density of Solution

Which variables goes on the x axis and y axis for the density and percent sugar of beverages experiment?

New cards

New cards

Calibration curve- allows for interpolation of unknown values

What purpose does the graph of standard solutions serve in Experiment #3?

New cards

New cards

The calibration mark

When you use a volumetric flask, where are you filling to?

New cards

New cards

Water would dilute the sugar solutions and mess with the concentration

Why must you shake out excess water from the plastic bottles and make sure they are dry in Experiment #3?

New cards

New cards

Mass of solute- mass of solvent stays at 50mL

In Experiment #3, are you changing the mass of solute or the mass of solvent?

New cards

New cards

All (three decimal points)

In Experiment #3, weigh each empty bottle without their lids and use ... of the available figures from the balance.

New cards

New cards

30 mL beaker

In Experiment #3, which container is used to estimate the amount of solute (sugar) to be added to the 250mL bottles?

New cards

New cards

plastic pipet

When filling the 50-mL volumetric flask with as much water as you can, make sure to use a ... to make sure not to overshoot the etched mark on the flask.

New cards

New cards

False- mass it once and assume it is the same for the rest of the solutions

True or False: In Experiment #3, you must get the mass of the empty 100-mL and the full of water 100-mL beaker each for each solution.

New cards

New cards

weighing by difference

the standard method for obtaining the mass of a liquid or another material that would be difficult to weigh on weigh paper (mass of full container - mass of empty container)

New cards

New cards

increases

Experiment #3: As the percent sugar increases, the density ....

New cards

New cards

Beaker (0 dp), Erlenmeyer flask (0 dp) graduated cylinder (1 dp), volumetric flask (2 dp),

List the following in order from least accurate to most accurate: graduated cylinder, beaker, Erlenmeyer flask, volumetric flask

New cards

New cards

3 decimal places

How many decimal places can a balance use?

New cards

New cards

The copper chloride hydrate; hydrochloric acid

What is highly toxic by ingestion and inhalation? What is also highly toxic and can be corrosive to the skin and eyes?

New cards

New cards

reaction stoichiometry

What process is used to determine the number of moles of each of the compounds of a hydrated binary salt?

New cards

New cards

In the appropriately labeled containers; NOT in the sink

How should the copper chloride hydrate be disposed of in Experiment #4?

New cards

New cards

The Law of Definite Proportions

a fundamental component of the modern atomic theory; the mole ratios of elements in a compound will be small whole numbers

New cards