Stoichiometry

1 gram is equal to: (A) 6.022⋅10^23 moles of Carbon (B) 6.022⋅10^23 moles of mass (C) 6.022⋅10^23 moles of atomic mass units (D) 6.022⋅10^23 moles of Helium

(C) 6.022⋅10^23 moles of atomic mass units

You have a substance that is composed of 20.8% Iron and 79.2% Chlorine by mass. What is the chemical formula of this compound (periodic table: http://www.chem.qmul.ac.uk/iupac/AtWt/table.gif)? (A) FeCl3 (B) Fe2Cl3 (C) FeCl6 (D) Fe3Cl6

(C) FeCl6 Pretend you have 20.8 g of Fe. That would be 20.8 g / 55.845 g -> approx. .33 moles Fe Pretend you have 79.2 g Cl. That would be 79.2 g / 35.45 g -> approx. 2 moles Cl. So, for every 1 Fe atom, you must have 6 atoms of Cl, making the formula FeCl6.

mole

- the SI base unit used to measure the amount of a substance - related to Avogadro's number

56g of C2H4 react with 32g of O2 to produce water and carbon dioxide. How many grams of water would be produced? A. 24g B. 27g C. 30g D. 32g

A. 24g The balanced formula is C2H4 + 3O2 -> 2CO2 + 2H2O. In the problem, two moles of C2H4 react with two moles of O2, thus O2 is the limiting reagent as the coefficient is 3 in the balanced equation. There will be 2/3 * 2 = 4/3 moles of water produced which equates to about 24 grams.

Which of the following compounds containing solely nitrogen and oxygen have an approximate composition of oxygen of 65%? A. NO B. NO2 C. N2O2 D. N2O3

D. N2O3 The molar mass of N2O3 is 76 g/mol and oxygen composes about 48 g/mol of that molar mass. 48/76 is approximately 65%.

The _________ Formula of Glucose is C6H12O6 while the _________ Formula of Glucose is CH2O. Fill in the blanks using the following options: - Empirical - Atomic - Molecular - Compound

The Molecular Formula of Glucose is C6H12O6 while the Empirical Formula of Glucose is CH2O.

empirical formula

a formula with the lowest whole-number ratio of elements in a compound

law of constant composition

all samples of a given compound have the same proportions of their constituent elements

equivalent (stoichiometry)

how many moles of "something" a molecule can donate i.e. Na+ can donate 1 mole of e- while Mg2+ can donate 2 moles of e-

gram equivalent weight

measure of the mass of a substance that can donate one equivalent of the species of interest

molarity

moles of solute/liters of solution

molecular formula

shows the kinds and numbers of atoms present in a molecule of a compound

percent composition

the percentage by mass of each element in a compound

molecular weight

the sum of the atomic weights of all the atoms in a molecule (i.e. molecular mass of glucose is mass of C6H12O6 = 180)

formula weight

the sum of the atomic weights of the atoms in the empirical formula (i.e. formula mass of glucose is mass of CH2O = 30)