Exam 1 Review

Molecular Structure

100

Pt 1:  What part of an atom has a mass? 

Pt 2:  What does the atomic number represent, and briefly what does that tell us / why is it important? 

Pt 1: The protons and Neutrons 

Pt 2: number of protons, and that if the # of protons changes, the element identity changes. (i.e, carbon will never have 6 protons)

200

Write out the Atomic Structure of an atom with an atomic mass of 27 and 14 neutrons, and identify the element. 

element: Al 

Protons: 13 

300

³²Ca

Break down the isotope values (e^-, P, N, mass, charge, name)

P: 20

N: 12

e^-: 20

charge: 0

mass: 32

name: calcium 

400

NO₂^-  has how many electrons and how many of those are valence?

24 total electrons and 18

500

What of these are molecules 

NaCl          PO₄^3-

CuO          P₂O₃

P₂O₃

(the others are compounds or an ion*)

Nomaclature

100

Potassium Chloride 

PCl

200

MgBr₂

magnesium Bromide

300

AsI₃

Arsenic Triiodide 

400

Magneisium Nitrate 

Mg(NO₃)₂

500

Ammonium sulfate 

(NH₄)₂SO₄

Isotope abundance/unit conversion

100

what of the following is an isotope 

³²₁₆S          ³⁴₁₆S

³²₁₈S          ¹⁶₃₂S

³⁴₁₆S

200

If I had 84.25L HCl and wanted vessels of 6280mL, how many vessels could I make? (sig figs)

13.4 vessels 

300

What is the most abundant isotope?

⁸⁰Sr  ⁹⁴Sr  ⁸⁸Sr  ⁸³Sr  ⁸⁷Sr

Sr ave molar mass: 87.62 g/mol

⁸⁸Sr

400

²⁷Al represents 80% of Al atoms, and ²⁶Al represents 20%. What is Al's molecular mass?

26.8 g/mol 

500

²¹Na is 16% of Na atoms, ²²Na is 22%, and ²³Na is 62%.

what is Na's molecular Mass 

(this is made up data, not real world)

22.46g/mol

Stoichiometry

100

238mL of a 2.36M CaCO₃ solution. 

How many moles of Calcium do I have?

0.562 moles Ca

200

I have 342.3g of Na₃P. How many moles of sodium are there? 

10.27 moles Na

300

23.53 g of NaCl reacts with excess LiOH. How many moles of NaOH are produced? 

0.4026 mol NaOH

400

0.245 mol of BeS reacts with 0.129 mol KBr. How many grams of K₂S are produced? 

27.0 g K₂S

500

I react 37.68g of CaCl₂ with 48.8g of Be₃P_2. What is my balanced equation and yield in grams of the compound containing calcium? 

3:1:3:1

yield: 20.6g Ca₃P₂ 

limiting reactant: CaCl₂ 

solution steps in notes (Sierra)

Chemical RXNs

100

_HCl + _MgF₂  ->  _HF + _MgCl₂

2HCl + 1MgF₂  ->  2HF + 1MgCl₂

2:1:2:1

200

What is the result Sr₃P_2(s) + H₂O_(l) -> ...? 

3Sr²⁺_(aq) + 2P^3-_(aq)

300

To make an apple pie, it takes a dozen apples and 4 cups of flour. If I have 137 apples and 45 cups of flour, how many pies can I make? 

11 (11.25)

400

Write out the dissolution reaction for H₂SO₄ and molar ion equivalence. 

products: 2H⁺ + SO₄^2-

mol. ion: 3

500

If I react  294.53 g MgCl₂ with 285.34 g Na₃P, what is the percent yield of the compound containing P (in the products)? Experimental yield is 43.57 g. 

Hint: will need to find its theoretical yield. 

%yield: 31.3%

MgCl_{2 MW}: 95.211g/mol

Na3P MW: 99.943 g/mol

molar ratio: 3:2:1

MgCl2 = LR

Mg3P2 MW: 134.863 g/mol

Theo yield: 139.06 g