Atomic Theory and Matter
A mixture that has the same composition throughout.
What is a homogeneous mixture?
How many significant figures are in:
0.0040500
5 sig figs
The positively charged particle found in the nucleus.
What is a proton?
Balance:
_ Al+_ O2→_ Al2O3
_4 Al+_ 3O2→_ 2Al2O3
How many moles are present in 36.0 g of H₂O?
2 mol
A student obtains the following measurements for the density of a metal:
7.21, 7.18, 7.20, 7.19 g/mL
The accepted density is 7.50 g/mL.
Is the student's data precise, accurate, both, or neither?
The measurements are very close to each other → precise.
But they're not particularly close to 7.50 → not accurate.
A student measures a liquid as 25.60 mL.
Convert this volume to:
a. liters
b. microliters
a. .02560 L
b. 25,600uL
Name HF(aq).
hydrofluoric acid
Write the correct formula for the compound formed between Al³⁺ and O²⁻.
Al2O3
How many grams of water can be produced from 10.0 g H₂, assuming excess O₂?
89.4 g H2O
A sample has a mass of 24.6 g and occupies 8.20 mL.
Calculate its density and determine whether it would sink or float in water.
Water density = 1.00 g/mL
Density = 3.00 g/mL → sinks
A student measures a sample as 9.82 g. The accepted value is 10.00 g. Calculate percent error.
1.8%
An atom has atomic number 17 and mass number 37. How many protons and neutrons does it have?
17 protons and 20 neutrons
Calculate the percent composition of oxygen in:
CaCO3
47.96%
41.2 g O₂ reacts with excess NH₃. Using
4NH₃ + 5O₂ → 4NO + 6H₂O
what is the theoretical mass of NO?
30.9 g NO
Explain the difference between a physical property and a chemical property and classify these:
Chemical - reacts to form new substance
Physical - does not change substance's identity
A car travels 68.5 miles/hour.
Convert this speed to meters/second.
30.6 m/s
Give the formula for:
A. Nitrate ion
B. Phosphate ion
C. Permanganate ion
A. NO3-
B. PO4 3-
C. MnO4-
A compound contains 52.14% carbon, 13.13% hydrogen, and 34.73% oxygen.
Determine the empirical formula.
C2H6O
Given:
2Al+3Cl2→2AlCl3
You react:
Find
1. Cl2 limiting
2. 43.9 g AlCl3
An element has two naturally occurring isotopes:
Calculate the element's average atomic mass.
(62.93)(0.6917)+(64.93)(0.3083) =43.51+20.01
63.52 amu
A deep-space scientific probe consumes propellant at a rate of 450.0 milligrams per millisecond of thruster operation. The density of the liquid propellant is 1.25 grams per cubic centimeter. If the probe carries a total propellant load of 180.0 kilograms, how many total hours of thruster operation can the probe sustain before depleting its fuel tank?
.111 hours
Chlorine is 75.77% Cl-35 and 24.23% Cl-37. Calculate its average atomic mass.
(35)(0.7577)+(37)(0.2423) =26.5195+8.9651 = 35.48 amu
A compound has the empirical formula:
C2H5O
Its molar mass is 180.0 g/mol.
Determine its molecular formula.
C8H20O4
2C2H6+7O2→4CO2+6H2O
A student burns 15.0 g C₂H₆ with 40.0 g O₂.
Determine:
A. The limiting reactant.
B. The theoretical mass of CO₂.
C. If the student actually collects 27.5 g CO₂, calculate the percent yield.
A. O2
B. 31.4 g CO2
C. 87.6%