Test on Thursday, December 1, 2016

Question 1

What does Accuracy mean? 3

Answer 1

It refers to how close the measurement is to the true value

Determined by the procedure used to obtain measurement

Improper method results in all values consistently too high or too low

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For example: A dart board

Accuracy — I get most of my darts around the centre. Not necessarily close together

Precision — All my throws land in the exact same area (whether or not it is close to the center)

Question 2

What are the three types of errors?

Answer 2

Random error

Systematic error

Gross error

Question 3

Define Anhydrous salt

Answer 3

When hydrates release water

Question 4

Give two examples on random error.

Answer 4

Uncertainty of measuring a liquid

Uncertainty of measuring mass

Question 5

What is L equal to? Also called Avogadro’s number

Answer 5

6.022×10²³

Question 6

What does STP mean? 3

Answer 6

It stands for Standard Temperature and Pressure

Standard Pressure is 100 kPa

Standard Temperature is 0°C

Question 7

How can Random error be reduced?

Answer 7

It can be reduced through repeated measure as it alters measurements equally on both sides of a value

Question 8

Define Gross error.

Answer 8

Recognized one time mistakes including spills, mislabeling and recording wrong value

Question 9

How do you calculate percent yield?

Answer 9

(Experimental yield/theoretical yield) * 100

Question 10

Define Formula Mass 1

Answer 10

Is the sum of the atomic mass of each ion in the empirical formula

(Used for ionic compounds)

k2O has 2 potassium and 1 oxygen
FM = 2(29.10g/mol)+(116.00g/mol)
FM = 74.2

Question 11

How many volume does one mol of any gas occupy at STP?

Answer 11

22.7 L

Question 12

Define Precision. 2

Answer 12

It refers to how close several measurements of the same quantity are to each other

It is determined by the device used to measure

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A graduated cylinder is more precise than a beaker for volume because its uncertainty is +- 0.5ml

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For example: A dart board

Accuracy — I get most of my darts around the centre. Not necessarily close together

Precision — All my throws land in the exact same area (whether or not it is close to the center)

Question 13

What do Chemical Reactions require? 3-6

Answer 13

New substances to be formed

Bonds of reactants to be broken and bonds of products to be formed
Results in an energy change (gain or loss)

Fixed ratios between reactants/products
Ratio in number of moles or particles
Called stoichiometry

Question 14

Give two examples of desiccants.

Answer 14

“Dry it” bag contains anhydrous calcium chloride to dehumidify the air

Silica gel is found in packages of many electronic devices

Question 15

Define Desiccant.

Answer 15

Anhydrous salts that will attract water out of the air to reform hydrate

Question 16

Define Molar Mass

Answer 16

A single atom has a very small mass

Question 17

What element and its isotope are all the masses given in the periodic table based on?

Answer 17

It is based on the isotope carbon-12

Question 18

What is mole or Avogadro’s number used for? 4 or 2

Answer 18

A very big number useful for counting small things like:

Atoms

Molecules

Ions

Formula Units

=======================

Mainly Converting from # of atoms to moles

and

Converting from # of moles to atoms

Question 19

Define Systematic error

Answer 19

Inherent in procedure and unnoticed in lab

Question 20

What is 22.7 L written as also? (how it is written in IB)

Answer 20

22.7 dm³

Question 21

What is the symbol of the molecular mass? (It is the same as Relative Atomic Mass)

Answer 21

Mr (the r is a subscript)

Question 22

What are Quantitative data? 2

Answer 22

Data from observations from sight, touch, taste, hearing and smell

May be prediction of unknown values or determination of slope of line or curve

Question 23

Define Molecular Mass 1

Answer 23

Is the sum of the atomic mass of each atom in the molecule

H2O has 2 hydrogen and 1 oxygen
MM = 2(1.01g/mol) + 1(16.00g/mol)
MM = 18.02

Question 24

Where are the three errors addressed, in what section?

Answer 24

The Evaluation section

Question 25

Define Atomic Mass

Answer 25

Weighted mean of all the isotopes of the element

Measure in grams per mole

Atomic mass of carbon-12 is 12.01 g/mol

Question 26

What are proper techniques that need to be used to reduce Systematic errors? 4

Answer 26

Measured from bottom of meniscus

Calibrated measuring devices (Tareing)

Properly prepared solution

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It is possible to have several precise readings taht are inaccurate
Like having a misaligned scope on a gun

Question 27

Define Structural Formula for Chemical formulas

Answer 27

Is shows structure like 3D diagrams from VSEPR

Question 28

What is the symbol of the relative atomic mass?

Answer 28

Ar (the r is a subscript)

Question 29

What are Qualitative data? 2

Answer 29

Variables are proportional, inversely proportional

Data is obtained from instruments

Question 30

What are metal ions chemically bonded to water molecules called?

Answer 30

Hydrated ions

Question 31

Why must anhydrous salts be stored in sealed containers?

Answer 31

To prevent moisture absorption

Question 32

What does the term Molar Mass be used for? What type of masses? 3

Answer 32

Atomic mass,

Atomic mass,

and Formula mass

Question 33

Define Empirical Formula for Chemical formulas

Answer 33

Lowest whole number ratio of atoms of each element in a substance

Ex. NaCl

Question 34

Define Stoichiometry

Answer 34

The relationship between the relative quantities of substances taking part in a reaction or forming a compound, typically a ratio of whole integers.

Question 35

What does the single arrow in a Chemical word equation mean? 2

Answer 35

“Yields”

Reaction goes to completion

Question 36

What is a Chemical (Word) Equation? 5

Answer 36

A chemical “sentence” that has:

Reactants on the left
Names or formulas of initial substances

Single-headed arrow means “yields”
Reaction goes to completion

Products on the right
Names or formulas of final substances

Quantities of each substance for complete reaction(Not for word equations)
Coefficients in front of fromulas

State symbols (Not for word equations)
     Solid (s), liquid (l), gaseous (g) or dissolved in water/aqueous (aq)

Question 37

Define Molecular Formula for Chemical formulas

Answer 37

Shows actual number of atoms of each element for a molecule

Ex. CH2O