Chem Lab Exam 1

Temperature is measured by?

Lab thermometer to the ±0.1 C

Mass is measured by? (two things)

analytical balance: ±0.0001g

Top loading balance: ±0.01g

measures volume within a range?

Graduated equipment

measures only one specific volume

volumetric equipment

How many sig figs for standard deviation?

1 sig fig unless the leading digit is 1, then use 2 sig figs

How many sig figs for average?

the same number of decimal places as the standard deviation

Agreement of repeated measurements?

Precision

Agreement between average and true value?

accuracy

how many sig figs for multiplication and division?

same amount of sig figs as the factor with the least sig figs

how many sig figs for addition/subtraction?

same amount of decimall places as the factor with the least decimal places

What is the formula for weight % of sugar

weight of sugar (g) / weight of solution (g) x 100%

Formula for density

Mass / volume

What is an oxide?

a binary compound of oxygen with other element

What is an anhydride?

an oxide when dissolved in water produces an acid or basic solution

What is an acid?

Substance when in water produces H+ (formula starts with H)

What is a base?

Substance when in water produces OH- (ends in OH)

If blue litmus paper turns red, we know the compound is?

Acidic

If red litmus paper turns blue, we know the compound is?

Basic

What are Halogens?

diatomic molecules, non-polar, strong electronegativity

What are Halides?

negatively charged ions

What is electronegativity?

the tendency to attract electrons to itself

Sodium Peroxide

Na2O2 - basic

Calcium Oxide

CaO - basic

Boron Trioxide

B2O3 - acidic

Carbon Dioxide

CO - acidic

Diphosphorous Pentoxide

P2O5 (or P4O10) - acidic

Sulfur Dioxide

SO2 - acidic

Dicholrine heptoxide

C2O7 - acidic

KF + Cl2 →

No reaction

2KBr + Cl2 →

2KCl + Br2

2KI + Cl2 →

2KCl + I2

KF + Br2 →

No reaction

KCl + Br2 →

No reaction

2KI + Br2 →

2KBr + I2

KF + I2 →

No reaction

KCl + I2 →

No reaction

KBr + I2 →

No reaction

Oxyacids

HClO_, HNO_, H2SO_, H3PO_, H2CO3

Naming Oxyacids: Prefixes

If the oxygen has a subscript of 1, the prefix is “hypo”; if the oxygen has a subscript of 4, the prefix is “per”, otherwise no prefix.

Naming Oxyacids: Root Word

Cl = Chlor; N = Nitr; S = Sulfur; P = Phosphor; C = Carbon;

Naming Oxyacids: Suffixes

Find the subscript on the oxygen. For HClO_, H2CO3, and HNO_if the subscript is 1 or 2, the suffix will be “ous” and 3 or 4 will be “ic”; For the rest, if 3 then “ous” if 4 then “ic”

Salts

NaClO_, KNO_, K2SO_

Naming Salts: Prefixes

If the subscript on the oxygen is 1 then prefix = “hypo” if 4 ONLY FOR NaCLO then “per”; otherwise the prefix will be the FULL name of the starting element.

Naming Salts: Root word

Cl = "Chlor”; N = “Nitr”; S = “Sulf”

Naming Salts: Suffixes

If the subscript for oxygen is 1 or 2 then “ite” if 3 or 4 then “ate”; EXCEPT for K2SO3 - suffix is “ite” and K2SO4 suffix is “ate”

Naming Compounds: Prefixes

The subscript on the element will be the prefix so: 2 = di, 3 = tri, 4 = tetra, 5 = pent, 6 = hex, 7 = hept, 8 = oct

Naming Compounds: Suffixes

For all that are only like 2 elements, add “ide” to the end. Oxygen2 → “dioxide

What are organic acids?

organic molecules with functional group

What are metal oxalate compounds?

compounds with metal ion surrounded by oxalate ions

Oxalate Ion

C2O4²-

Oxilic Acid

H2C2O4

Why was KOH added to the aluminum turnings

aluminum reacts with strong base (KOH) to dissolve the aluminum and form soluble tetrahydroxoaluminate or Al[OH]4^-

Why is oxilic acid dihydrite added?

it provides the oxalate ions (C2O42−) needed to form the final aluminum oxalate complex, [Al(C2O4)3]3−.

Why is K2C2O4•H2O added to CuSO4•5H2O

it provides the oxalateions (C2O42−) that bond to Cu²⁺ to form the desired complex, K₂[Cu(C₂O₄)₂]·hydrate.

why are both products washed with ethanol?

ethanol helps remove leftover water and impurities while keeping the desired solid product from dissolving

CuSO4.5H2O(aq) + 2K2C2O4.H2O(aq) →

K2[Cu(C2O4)2].nH2O(s) + K2SO4(aq) + (7-n)H2O(l)

2Al(s) + 6KOH(aq) + 6H2C2O4. 2H2O(aq) →

2K3[Al(C2O4)3].nH2O(s) + 3H2(g) + (18-2n)H2O(l)

Reactivity increases or decreases when going down a group of metals?

increases

Electronegativity increases or decreases down a group?

decreases