Stoichiometry

Multiple Choice

2HI + PbSO₄ -> PbI₂ + H₂SO₄

Does the above reaction satisfy the law of conservation of mass?

(Select all that apply)

• Yes, because there are the same number of atoms of each element on both the reactants and the products.

• Yes, because there are two reactants (HI & PbSO₄) and two products (PbI₂ & H₂SO₄)

• No, because there are three molecules on the reactant side and only two molecules in the product side

• No, because both the H and the I have a subscript of "1" on the reactant side and they have asubscript of "2" on the product

Multiple Choice

A fast food restaurant offers a Single breakfast consisting of 2 Eggs, 1 Toast, and 1 Bacon Slice and a Double breafkast with 4 Eggs 2 Toast and 2 Bacon Slices:

6E + 3 T + 3 B -> E₂TB + E₄T₂B₂

_{How many eggs are needed to make 10 Singles and 8 Doubles?}

• 52

• 18

• 26

• 42

Multiple Choice

What would be valuable information on a reaction model to show that conservation of mass is conserved?

• The molecular formula and the relative number of molecules involved in the reaction (stoichiometric coefficients).

• The boiling point of each reactant and product

• The bond energy between each atom in the reactants and products.

Multiple Choice

Consider the chemical equation CH₄ + 2 O₂ → CO₂ + 2 H₂O. In this equation, CH₄ is a

• product

• reactant

• displacement

Multiple Choice

What is the left part of a chemical equation called?
H_{2 +} O → H₂O

• Reactants

• Products 

• Yields 

• Chemical Equation 

Multiple Choice

What is the right part of a chemical equation called?
H_{2 +} O → H₂O

• Reactants

• Products 

• Yields 

• Chemical Equation 

Multiple Choice

2H₂ + O₂ ----> 2H₂O What is the product?

• ------>

• 2H₂O

• 2H₂+ O₂

Multiple Choice

The calculation of quantities in chemical reactions is a subject called

• stoichiometry

• magic

• mystery

• counting

Multiple Choice

Mole ratios are obtained from the

• balanced chemical equation

• periodic table

• molar mass

Multiple Choice

What is the mole ratio of H₂O to H₃PO₄ in the following chemical equation?   P₄O₁₀ + 6 H₂O --> 4 H₃PO₄ 

• 6:4

• 4:6

• 1:3

• 3:1

Multiple Choice

For the Balanced Reaction: 3 Mg + 1 Fe₂O₃ → 3 MgO + 2 Fe; What is the Ratio of moles of MgO to moles Fe?

• 3mol Mg / 2 mol Fe

• 2 mol Mg/ 3 mol Fe

• 1 mol Fe/ 2 mol Fe

• 3 mol MgO / 2 mol Fe

Multiple Choice

What is the mole ratio in the following reaction:
2CO  +  O₂  → 2CO₂

• 2:1:2

• 1:1:1

• 1:2:1

• Have no clue what a mole ratios is!!

Multiple Choice

What is the Law of Conservation of mass?

• Mass is created in a chemical reaction

• Mass is created in a physical change

• New chemicals formed from a chemical reaction have a larger overall mass than the original reactants

• Mass is never created or destroyed

Multiple Choice

In a reaction A + B ----> C,  reactant A has 5g and product  C has 9g. How many grams does reactant B should have? 

• 4g

• 5g

• 9g

• 14g

Multiple Choice

The number in front of a compound or element is a 

• Subscript

• Coefficient

• Superscript

• Charge

Multiple Choice

The number to the lower side of an element is a 

• Subscript

• Superscript

• Coefficient

• Charge

Multiple Choice

Matter can not be created nor destroyed: it can only be

• Destroyed a little bit

• Invisible

• Transformed, changed

• None of the above

Multiple Choice

Which is Chemical Equation is Balanced?

• CH₄+O₂------CO₂+2H₂O

• H₂+O₂-----2H₂O₄

• 4Al+3O₂-----2Al₂O₃

Multiple Choice

Is this equation balanced or unbalanced? 
2Fe₂O₃ + 3C --> 4Fe + 3 CO₂

• balanced

• unbalanced

Multiple Choice

Which of the following represent a mole ratio between silver nitrate and copper(II) nitrate in the following reaction:
2AgNO₃ + Cu --> Cu(NO₃)₂ + 2Ag

• 2 mol AgNO₃ / 2 mol Ag

• 2 mol Ag / 2 mol AgNO₃ 

• 2 mol AgNO₃ / 2 mol Cu(NO₃)₂

• 2 mol AgNO₃ / 1 mol Cu(NO₃)₂

Multiple Choice

4NH₃ + 5O₂-->4NO + 6H₂O
What is the total number of moles of H₂O produced when 4 mole of NH₃ is completely consumed?

• 15
• 6

• 2

• 5

Multiple Choice

Using the following equation:
Fe₂O₃(s) + 3H₂(g) → 2Fe(s) + 3H₂O(l)
How many moles of iron can be made from  3 moles H₂? 

• 4 moles Fe

• 6 moles Fe

• 9 moles Fe

• 2 moles Fe

Multiple Choice

N₂ +  3H₂ → 2NH₃ 
How many moles of hydrogen are needed to react with 1 mole of nitrogen?

• 6

• 2

• 3

• 1

Multiple Choice

2H₂   +   O₂  →  2H₂O
How many moles of water can be produced if 2 moles H₂ are used?

• 4 moles

• 8 moles

• 16 moles

• 2 moles

Multiple Choice

Using the following equation:
Fe₂O₃(s) + 3H₂(g) → 2Fe(s) + 3H₂O(l)
How many moles of iron can be made from  6 moles H₂? 

• 4 moles Fe

• 6 moles Fe

• 9 moles Fe

• 2 moles Fe

Multiple Choice

2 KClO₃ → 2 KCl + 3 O₂

How many moles of oxygen are produced when 6 moles of KClO₃ decompose completely?

• 6 mol

• 1.0 mol

• 9 mol

• 3 mol

Multiple Choice

2 KClO₃ → 2 KCl + 3 O₂

How many moles of KCl are used when 4 moles of KClO₃ decompose completely?

• 6 mol

• 1.0 mol

• 9 mol

• 4 mol