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MSU / Engineering / CHEM 120 / What is the meaning of limiting reactant?

# What is the meaning of limiting reactant? Description

##### Description: This covers all material (Chapter 3,4,5, and 6) that will show up on the test!
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H+O= acid

## What is the maning of limiting reactant? Ex. HCL: Hydrochloric acid

Molar Mass

What is the molar mass of C8H18?

8(12.01g/mol) + 18(1.01 g/mol)= 114.22 g/mol

Glucose formula: C6 H12 O6

Therefore 1 mole of Glucose…

Is 6 mole of C

Is 12 mol of H

Is 6 mol of O

Empirical and Molecular formula

Empirical formula: the simplest ratio present

Ex: CH2O

Molecular formula: n (empirical formula)

Ex: C6H12O6 = 6 (CH2O)

Molar mass: n (empirical mass)

Ex: (6 x 12.01 g/mol) + (12 x 1.01 g/mol) + (6 x 16.000 g/mol) = 180.16 g/mol (MOLAR MASS)

## What doe electrolytes contain? Ex. (1 x 12.01 g/mol) + (2 x 1.01 g/mol) + (1 x 16.000 g/mol)= 30.03 g/mol (EMPIRICAL MASS)

Examples: What’s the empirical and molecular formula of the following compound? 26.7% P, 12.2% N, 61.2% Cl Molar Mass: 580 g/mol

Strategy: Assume 100 g of compound

P: 26.7 g; N: 12.2 g; Cl: 61.2 g

P: 26.7 x 1mol/30.97 g =0.862 mol P

N: 12.2 x 1mol/14.01 g =0.864 mol N

Cl: 61.2 x 1mol/35.45 g =1.73 mol Cl

Divide by smallest number: 0.862

P: 0.862/0.862 N: 0.864/0.862 Cl: 1.73/0.862=

P1 N1 C2 ---->> EMPIRICAL FORMULA

For molecular….

Molar mass= n ( empirical mass)

## How can one compute for glucose? 580 g/mol= n (30.97g/mol + 14.01 g/mol + 2(35.45g/mol)) Don't forget about the age old question of What are the police misconducts identified by ellwyn stoddard?

580 g/mol= n (115 g/mol)

n= 5.04--------> 5

Molecular formula:

=5(empirical formula)

=5( PNCl2)

=P5N5Cl10

Limiting reactant: reactant that is entirely used up and makes less product Theoretical yield: maximum amount you can make

Percent reactant: actual yield/ theoretical yield x 100%

Excess reactant: reactant that has left overs

How to balance equations: ____Fe (s) +___ O2 (g) ------>>> ___ Fe2O3 (s) 1. Start with 1.00 mol O2, How many moles Fe needed?

1.00 mol O2 x 4 mol Fe/ 3 mol O2 = 1.33 moles of iron Don't forget about the age old question of How is eversion performed?

2. Start with 100 g O2, How many grams Fe needed? If you want to learn more check out How the allocation of resources affects economic well being?

100.0 g O2 x 1 mol O2/ 32.00 g x 4 mol Fe/ 3 mol O2 x 55.85 g Fe/ 1 mol Fe= 232.7 grams Fe

3. Start with 32.7 grams O2 with 54.1 grams Fe, How much Fe2O3 possible?

Fe

O2

Fe2O3

Mass before

reaction

54.1 g

32.7 g

0g

Moles before

(54.1x 1 mol)/

55.85g.=0.969

mol

1.02 mol

0 mol

Moles after

0 mol

0.295 mol

0.484 mol

Mole after

reaction

0 mol

0.295x 32.00 g/ 1 mol

0.484 x 159.70g/1 mol

If you want to learn more check out What are types of species distribution patterns?

__4__Fe (s) +_3__ O2 (g) ------>>> _2__ Fe2O3 (s)

Chapter 5: Solutions

Solution: homogeneous mixture of solvent and solute

Solvent: large amount of what is dissolving solute (Ex. water)

Solute: smaller quantity

Molarity (M): moles of solute/ L of solution

Ex. 0.500 M NaCl, whats the molarity of Na+ and Cl-?

0.500 M for each

DISSOLVE VS DISSOCIATE

Dissolve: solid and solvent form homogeneous mixture

Dissociate: ionic compound falls apart into ions as it is dissolved in solution

Electrolytes- solution that contains ions

Strong electrolytes: “fully dissociate”

= solution that conducts electricity

Weak electrolytes: “partially dissociates”

Non- electro. : does not dissociate (Ex. sugar, gasoline, oil) ;won’t conduct electricity

NaCl ( table salt ) in H20 will dissociate because it is ionic ( NaCl------>> Na+ + Cl-) C12H24O12 (sugar/sucrose) won't dissociate but will dissolve Don't forget about the age old question of Where is the temperate broadleaf forest?

Mostly Soluble:

1.anything (anion) with group 1 cation( Li+, Na+, K+) and ammonium 2. anything (cation) with nitrate or acetate

3.Group 17 anion

Exception:Ag+, Hg2^2+, Pb^2+

4.SO4^2-

Mostly insoluble:

1.OH-, S2- We also discuss several other topics like Why are the offspring of sexual reproduction not perfect copies of their parents?

2.CO3^2-, PO4^3-

ACID

*Strong acid: HCl, HI, HNO3, H2SO4, HClO4 (MEMORIZE)

Weak acid: everything else

BASE

Strong base: NaOH, LiOH, KOH, Ca(OH)2

Weak base: NH3

acid+ base-----> H2O +SOH

Strong acid + Strong Base

Ex. HCL + NaOH---> H20 +NaCl

H + Cl + Na+ OH -----> H2O + Na +Cl

CROSS OUT REPEATS!

H+ OH----> H2O

OXIDATION

Oxidation state= Oxidation number : ELECTRONS!!

Oxidation number= charge on ion!!! (sign first)

1.Neutral elements have oxidation of 0

Ex. H2, He, Fe

2.monoatomic ions

a.Ex. H+, Na+, K+, Li+---≥ lose one electron so oxidation is +1

b.F-, Cl-, Br-, I- ----> gain electron so oxidation is -1

3. H in molecule is +1

4.O in molecule is -2

5.Group 17:-1

6.Group 1: +1

7.Group 2: +2

Chapter 6

PV=nRT(memorize)

Pressure(atm) x volume( L)= mols of gas(mols) x gas constant (0.08206) x temperature (K) 1 atm= 760mmHg

Ex. If you fill a balloon with 5.00 grams of He gas at 298 K and 1.00 atm pressure, what's the V of the balloon?

PV=nRT

P= 1.00 atm

v=?

n= 5.00 g x 1mol/4.00 g= 1.25 mols

R= 0.08206

T= 298 K

1.00(V)= (1.25)(0.08206)(298)

V= 30.6 L

Collecting gas over water

Ptotal = Pgas( from reaction) + PH2O( evaporate)

Theory of Gas:

1. The size of a gas atom/ molecule is really tiny compared to the volume of gas 2. The average kinetic energy of atom/molecule depends on temp of gas 3. (KE=.5mv^2)(higher temp means higher velocity and higher KE)

4. Same temperature, different gas

a. KEgas1= KEgas2….

5. Same gas, different temperature

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