Unit 7 (Incomplete!) Flashcards
What’s a mole used to count?
A mole is used to count atoms and molecules that are too small to count by usual means
Molar mass of a substance is its…
Molar mass of a substance is its average atomic mass in grams from the periodic table
STP
Standard temperature and pressure
Molar volume
22.4 L/mole for any gas @ STP
Diatomics definition
Molecules that exist as element2 when alone.
Diatomics
HNOFClBrI
SI base unit for the amount of substance
Mole
What’s true about the molar mass of chlorine gas
a. the molar mass is 35.5 g
b. the molar mass is 71.0 g
c. the molar mass is equal to the mass of 1 mole of chlorine gas
B. The molar mass is 71.0 g
What do diatomics like Cl exist as when alone?
Cl2
Representative particle
Smaller particles that represent larger particles
Atoms represent molecules
Cations + Anions represent ionic compounds like NaCl (Na+, Cl-)
Density @ STP of the gas sulfur hexafluoride
6.52 g/L
STP
Standard temperature and pressure:
- 0* Celsius
- 1 atm = 22.4 L
Which of the following is a representative particle?
a. atom
b. cation
c. anion
d. all of the above
d. ALL OF THE ABOVE
What does the empirical formula show?
The empirical formula shows the lowest/simplest whole-number ratio in which the atoms of the elements are present in the compound
What does the molecular formula show?
The molecular formula shows the actual number of atoms of each element in one molecule of the substance.
Or the multiple of the lowest whole-number ratio of elements in a compound
Which term is described as the percent by mass of any element in a compound?
Percent Composition
To determine the formula of a new substance, one of the first steps is to find the ____.
Percent Composition
What information is needed to calculate the percent composition of a compound?
The formula of the compound and the atomic mass of its elements
Which of the following compounds have the same empirical formula?
a. C2H4 and C8H16
b. CO2 and SO2
c. C6H12 and C6H14
d. C4H10 and C10H4
A. C2H4 and C8H16
What volume is occupied by 12.5 moles of nitrogen gas at STP?
280 L
How to calculate percent error
((Theoretical (actual) - Experimental)/ Theoretical) x 100
A compound is composed of 85.64% carbon and 14.36% hydrogen. The compound has a formula mass of 42.08 grams. What is the molecular formula?
C3H6
What’s an Isotope?
Isotopes are atoms with the same number of protons but that have a different number of neutrons.
What’s an ion?
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge.
