C125 NEED TO KNOW AND STUDY!!!

Solubility Rules: Sulfates SO2-4

All sulfates are soluble except Ba2+, Pb2+, Ca2+ & Sr2+

Four general types of reactions:

Combination, decomposition, single-displacement, double-displacement (metathesis)

Why use DI water instead of tap water?

DI water is stabilized to room temperature (environment) compared to DI tap

Ideally, an equivalent amount of NaOH will be used to neutralize the acetic acid CH3COOH and this is called

the equivalent point

Random errors affect

the precision or scatter of results because of random fluctuations in the instruments or procedures

Percent Concentration includes

volume percent concentration and mass percent comcentration

If acids or bases ionize incompletely, they are called

weak acids or weak bases

What does each variable represent in y=mx+b?

y = outcome (y value) m = slope x = input (x-value) b = y-intercept

What is used to characterize accuracy?

% error

If plotting Volume on the y-axis, what do you need to plot on the x-axis?

1/P since inverse relationship PV and slope would be V/P

How many Pa in 1 atm?

101,325 Pa

How many psi in 1 atm?

14.7 psi

Mass % concentration of 5g of acetic acid in every 100g of solution?

5% acidity

How many Torr in one atm?

760

How many mm Hg in 1 atm?

760 mm Hg

Partial pressure of CO2 if the Patm is 98.5 kPa and vapor pressure 3.169 kPa?

95.4 kPa or 0.9413 atm Patm- P water vapor

Example of weak acid

Acetic acid CH3COOH

Solubility rules: Acetates C2H3O2

All acetates are soluble (except Ag)

Solubility Rules: Carbonates CO2-3 and Phosphates PO3-4

All carbonates and phosphates are insoluble except those of Na+, K+ & NH4+

Solubility Rules: Cl- Br- I-

All chlorides, bromides and iodides are soluble except Ag+, Pb+ & Hg2+

Solubility Rules: Hydroxides OH-

All hydroxides are insoluble except those of Na+ & K+. Ba2+ and Ca2+ are sligthly soluble

Solubility rules: Nitrates NO3

All nitrates are soluable

Solubility Rules: Na+, K+, NH4+

All salts of the sodium and potassium and ammonium ion are soluble (mostly)

Solubility Rules: Sulfides S^2-

All sulfides are insoluble except those of Na+, K+, NH4+ and those of alkaline earths: Mg2+, Ca2+, Sr2+ & Ba2+

Example of weak base

Ammonia NH3

The zero on the pressure gauge actually corresponds to?

Atmospheric pressure

Molar mass of a gas is 16g/mol. If avg molar mass of air is 29g/mol... will the balloon rise or sink?

Balloon would rise

Regression Statistics provides?

Best fit line equation and R^2 (goodness of fit) R^2 values greater than .95 are good

Predict CaCO3(s) + HCl oberservations

Bubbling since CO2

How can random errors be reduced?

By carrying out multiple trials and averaging the results

How can systematic errors be eliminated?

By paying careful attention to detail and understanding of proper use of equipment

Net Ionic equation

Chemical equation only including the ions or molecules directly involved in the reaction

To obtain density, what has to be the independent and dependent variable? What is the density?

D=m/v Therefore, mass is the dependent and volume is independent. Slope is the density

Extrapolation

Extending the best fit line outside the range of measured data at either the high or low end

Four categories of a double displacement/metathesis reaction?

Formation of a precipitate, formation of a gas, formation of water & formation of a soluble weak electrolyte

What happens when an acid and base are mixed? (Acid-base reaction or neutralization)

H+ from the acid (weak or strong acid) combine with the OH- from the base to form H2O

7 common strong acids

HCl, HBr, HI, H2SO4, HNO3, HClO3, HClO4

Common strong bases include

Hydroxides of group IA andn larger member of group IIA Mentals such as NaOH, KOH and Ba(OH)2

List the halogens Br2, I2 and Cl2 in order of increasing activity and explain why

I2<Br2<Cl2 The brown color showed that Bromide was produced, proving that chloride is strong since it displaced the bromide from the solution The pink color (Iodine) was produced in the other experiment showing that the Iodine was displaced by the bromide

Spectator ions

Ions that do not participate in the actual reaction and are omitted

Why is it important to use the same balance when weighing?

It ensures the same units and differences there could be between scales

What does it really mean when a pressure gauge reads zero?

It means that real pressure - atmospheric pressure = 0

What equation to use when comparing the Molarity and Volume?

M1V1=M2V2

Mass % concentration

Mass of solute divided by mass of solution times 100%

Precision

Measure of how close each measurement is to the other measurements

Accuracy

Measure of how well experimental results are to the actual literature values

Therefore, many weak acids and bases are written in?

Molecular forms

Predict NaOH + H2SO4 observations

No obvious obersvations

How many sig figs should the standard deviation have? And that limits the sig figs for what?

One; average/mean value

Boyle's Law

P1V1 = V1V2 constant n & T

Rearranged Ideal Gas Law equation to determine slope?

P= (1/V)nRT/ nRT is the slope

Ptotal = ?

Patm = Pgas + Pwater vapor

Partial pressure is basically?

Pgas

Pcorrected = ?

Pgauge + Patmosphere

Are equivalent points possible to reach? What are used instead?

Practically impossible; pH indicators are used to determine end point of titration

Predict Pb(NO3)2 + Na2SO4 observations

Precipitate cause of PbSO4

Formation of a soluble weak electrolyte reaction

Reaction in which acetic acid (CH3COOH) a weak electrolyte only dissociates partially. Formation of HC2H3O2 ?

Gas-forming reaction

Reaction in which ions are removed from a solution creating a driving force (gas produced)

Acid-Base reaction (Formation of water) Reaction

Reaction where an acid and base are mixed and a water and salt is produced; Also called acid-base neutralization

Real footballs are to be inflated between 12.5 psi - 13.5 psi. Some game balls were 10 psi. What is the real air pressure inside a 10 psi game ball?

Real P = Patm + pgauge 10 + 14.7 = 24.7 psi

Process of gaining an electron

Reduction

Interpolation

Results lie within the range of measured data

Common product of acid and base

Salt and water

For the equation lnN/lnNo = -kt what is the slope and y-int?

Slope is -k and y-intercept is lnNo

Why must you record the volume only when the height of the column of water inside the graduated cylinder is the same as the liquid level in the trough?

So that the pressure inside the cylinder is the same as the atmospheric pressure

Equation for standard deviation?

Square root of each value minus the average/mean squared, added with each other and divided by n-1

What is used to present precision?

Standard deviation

What are strong electrolytes?

Strong acids, strong bases and soluble ionic salts

When writing ionic equations, only ______ are written in ionic forms?

Strong electrolytes

When waiting long enough, the light pink color from titration may disappear due to CO2 from the air, why?

The CO2 reacts with the water in the solution to dorm carbonic acid and the light pink color disppears

AgNO3 is colorless but when red copper wire is added the solution changed to light blue and the copper is grey. What is causing the solution color to change from colorless to light blue? What is the shiny grey stuff on the copper wire?

The Cu2+ ion; silver

The total pressure of the gas and water vapor collected inside a graduated cylinder is equal to?

The atmospheric pressure outside the cylinder if the height of the water inside the cylinder is the same as the liquid level in the trough

Before titration , if a student rinsed the buret with DI water instead of NaOH solution, how will that affect mass % concentration? what if some of the NaOH solution remained on the wall of the flask and never reach the rxn mixture?

The concentration would be higher; the volume would be high making the experimental result higher

For the Gas Laws lab, students are asked to leave water in the trough so that the water will be ready for other labs? Why can't we use DI water from the faucet directly?

The water from the faucet is not at room temperature like the DI water we are using. (DI water should be close to room temp)

Why rinse the burets with NaOH solution instead of DI water before titration?

Using DI water could possibly mess up the NaOH concentration; we want the buret to only contain NaOH

Charles's Law

V1/T1 = V2/T2 constant n & P

For PV=nRT, what is the formula rearranged to y=mx+b and what is the slope and y-intercept?

V=(nR/P) * T Slope = RT/P Y-intercept = 0

Acid-Base reactions usually produces what?

Water and ionic compound (salt)

Precipitation reaction

When two substances result in the formation of an insoluble solid

Changes such as in color or state of matter often indicate a chemical reaction has occurred, if there is no obvious change when two solutions are mixed, can we conclude that there is no reaction?

Without obvious changes, it is not enough to conclude that there is no reaction. Some reactions may need additional things to see changes, such as pH indicator or it's just slow

When writing the Net Ionic Equation, what should you do first?

Write down balanced equation then total ionic equation then cancel out to get net ionic

Standard deviation follows what format?

X +- S (average plus or minus s.d.)

When the y-intercept is zero, the slope is?

Y/X

Y-intercept is the y-value when x is?

Zero

Acid-Base titration

analytical method to determine the concentration of an unknown acid or base

Though many weak acids and weak bases still dissolve in water, they only ________ __________ into ions and majority remain __________

dissociate partially; molecules

M = ? How is it plugged into the Ideal gas law equation when moles is not given?

m/n (mass over number of moles) PV=(m/M)RT

density (d) = ?

m/v or PM/RT

For the Ideal gas law equation PV=nRT with constant temperature and pressure, what is plotted on the X and Y axis?

n = x-axis v = y-axis

Molarity

number of moles of given solute dissolved in 1 Liter of solution; unit mol/L

Process of losing an electron

oxidation

Dependent Variable

quantity that you measure in the lab (outcome)

Independent Variable

quantity you control in the experiment

If acids or bases ionize completely, they are called

strong acids or strong bases

Acids are substances

that produce H+ ions in an aqueous solution

Bases are substances

that produce OH- ions in an aqueous solution

Systematic errors affect

the accuracy of the measurement ex. improper calibration, contamination, etc.