CHEM Lecture Homework Questions
Convert -20.7 °C to K.
252.5 K
Determine the formula weight of Al₂(SO₄)₃
342.14 amu
Convert 3.2 ft^2 to square inches
460 in^2
Balance the following chemical equation (if necessary):
V₂O₅(s) + 6 HCl(aq) → 2 VOCl₃(s) + 3 H₂O(l)
Complete the balanced neutralization equation for the reaction below:
2 HC₂H₃O₂(aq) + Sr(OH)₂(aq) → Sr(C₂H₃O₂)₂(aq) + 2 H₂O(l)
An irregularly-shaped piece of aluminum (Al) has a mass of 77.7 grams. What is the volume in cm³ of this piece of aluminum if its density is 2.70 g/cm³?
28.8 cm³
Convert 801 nanograms to milligrams.
8.01 × 10⁻⁴ mg
How many electrons are in a neutral ⁴¹Ca atom?
B) 20
Write the balanced NET ionic equation for the reaction when BaCl₂ and ZnSO₄ are mixed in aqueous solution. If no reaction occurs, simply write only NR.
Ba²⁺(aq) + SO₄²⁻(aq) → BaSO₄(s)
Determine the number of protons (p) and electrons (e) in Mg²⁺.
C) 12 p, 10 e
What numbers belong in the blank spaces to fully balance the following reaction? __Fe (s) + __Cl₂ (g) → __FeCl₃ (s)
C) 2,3,2
Write the chemical formula for the carbonate ion
CO₃²⁻
Based on the positions of the following elements on the periodic table, which of them would you expect to form a 3+ cation?
E) Both A and B Scandium & Aluminum
Which of the following is NOT a type of scientific observation?
E) Hypothetical
What does the mass number of an atom represent?
E) total number of protons and neutrons in the atom
Complete the balanced dissociation equation for the compound below in aqueous solution. If the compound does not dissociate, write NR after the reaction arrow.
Mg(OH)₂(s) → NR
Write the balanced NET ionic equation for the reaction when Pb(NO₃)₂ and KI are mixed in aqueous solution. If no reaction occurs, simply write only NR.
Pb²⁺(aq) + 2I⁻(aq) → PbI₂(s)
What is the correct IUPAC name for Al₂(SO₃)₃?
aluminum sulfite
Density is defined as mass _____________ volume.
D) divided by
Write the chemical formula for the ammonium ion
NH₄⁺
100.0 mL of a 0.605 M solution of KBr is diluted to 500.0 mL. What is the new concentration of the solution?
0.121 M
What is the molarity of potassium ions in a 0.122 M K2CrO4 solution?
0.244 mol K+ ion / L
Determine the mass in grams of 1.6x10^-3 mol glucose, C₆H₁₂O₆
0.29g
Convert 16.0 inches to meters. (2.54 cm = 1 inch)
0.406 m
An unknown element is a mixture of isotopes ¹²⁰X and ¹²²X. The average atomic mass of X is 121.03 amu. What is the percent abundance of ¹²²X?
51.5 %
Cathode rays are composed of what fundamental particle?
D) Electrons
An iron-containing compound is 20.1% Fe, 11.5% S, 63.3% O, and 5.1% H. What is the empirical formula for this compound?
D) FeSO₁₁H₁₄
A compound containing Na, C, and O is found to have 1.06 mol Na, 0.528 mol C, and 1.59 mol O. What is the empirical formula of the compound?
D) Na₂CO₃
What is the correct IUPAC name for HBrO(aq)
hypobromous acid
The uncertainty in the measurement 0.0035 mg is
D) ± 0.0001 mg
How many moles of NaOH are there in 335.0 mL of 2.50 M NaOH?
0.838 mol
Consider the following image of two buret measurements, the initial and final readings. What is the total volume of liquid delivered in mL?
16.77 mL
What is the percent by weight (w/w%) of sugar in soda? Assume the average mass of sugar in soda is 34.0 g and the total mass is 370.0 g.
9.19 %
Which of the following is an example of an intensive property of a bar gold?
A) The bar has a density of 19.2 g/mL.
Which one of the following is an example of a homogenous mixture?
A) coffee
Which is a method for separating a liquid-liquid mixture, such as water and acetone?
A) distillation
Which has the correct name-formula combination?
C) Carbon tetraiodide - CI₄
What is the correct IUPAC name for HC₂H₃O₂(aq)?
acetic acid
How many moles of Ag are in 87.1 grams of Ag₂O?
0.752 mol
If 0.250 L of a 6.40 M HNO₃ solution is diluted to 2.00 L, what is the molarity of the new solution?
0.800 M
Determine the mass in grams of 6.58 × 10²¹ atoms of arsenic. (The mass of one mole of arsenic is 74.92 g.)
0.819 g
An unknown compound is processed using elemental analysis and found to contain 117.4 g of platinum, 28.91 g of carbon, and 33.71 g of nitrogen. Given that you have 0.6017 moles of platinum, 2.407 moles of carbon, and 2.406 moles of nitrogen in the compound, determine the empirical formula of the unknown compound.
E) PtC₄N₄ or Pt(CN)₄
An unknown compound is processed using elemental analysis and found to contain 117.4 g of platinum, 28.91 g of carbon, and 33.71 g of nitrogen. The chemical formula of the compound is Pt(CN)₄. What is the IUPAC name of the unknown compound?
platinum(IV) cyanide
Write the balanced COMPLETE ionic equation for the reaction when KOH and Cu(NO₃)₂ are mixed in aqueous solution. If no reaction occurs, simply write only NR.
2 K⁺(aq) + 2 OH⁻(aq) + Cu²⁺(aq) + 2 NO₃⁻(aq) → Cu(OH)₂(s) + 2 K⁺(aq) + 2 NO₃⁻(aq)
An unknown compound is processed using elemental analysis and found to contain 117.4 g of platinum, 28.91 g of carbon, and 33.71 g of nitrogen. How many moles of nitrogen are present in the compound?
2.406 mol
An unknown compound is processed using elemental analysis and found to contain 117.4 g of platinum, 28.91 g of carbon, and 33.71 g of nitrogen. How many moles of carbon are present in the compound?
2.407 mol
The mass of a piece of metal is 20.7651 grams. When the piece of metal was dropped into a graduated cylinder that had an initial water volume of 5.35 cm³, the total volume was 13.34 cm³. What is the density of the piece of metal in g/cm³?
2.60 g/cm³
A thermometer reads 19.7 °C. What is the temperature in Fahrenheit?
67.5 °F
The element antimony (Sb) has an atomic mass of 121.76 amu. Two naturally occurring isotopes of antimony are ¹²¹Sb (57% abundant) and ¹²³Sb (43% abundant). In a sample of 100 Sb atoms, what is the probability that a single selected atom has a mass of 121.76 amu?
A) 0%
The answer to the calculation below with the correct number of significant figures is
A) 0.0822
How many protons (p) and electrons (e) are found in a Se²⁻ ion?
A) 34 p, 36 e
Which of the following does NOT describe the element bromine (Br)?
A) A metalloid
Balance the following chemical reaction: Al₂(SO₄)₃ (aq) + K₃PO₄ (aq) → AlPO₄ (s) + K₂SO₄ (aq)
A) Al₂(SO₄)₃ (aq) + 2 K₃PO₄ (aq) → 2 AlPO₄ (s) + 3 K₂SO₄ (aq
Determine the correct formula for aluminum oxide.
A) Al₂O₃
What is the formula of a compound containing Al³⁺ and S²⁻ ions?
A) Al₂S₃
Which of the following is a physical change?
A) Condensation forms on cold glass.
Classify the following compounds as ionic or covalent: OF₂, CuO, SeO₂.
A) Covalent, ionic, covalent
A mass spectrometer measures neon to have two masses: 20 and 22 atomic mass units. These are:
A) Isotopes
A homogeneous mixture is also called a ____________.
A) Solution
You measured the mass of a dry powder on a balance to be 23.76 g. What would you report as the uncertainty of this measurement?
A) ± 0.01
Complete the balanced dissociation equation for the compound below in aqueous solution. If the compound does not dissociate, write NR after the reaction arrow.
AgI(s) → NR
If 35.0 g of CH₃OH (MM = 32.0 g/mol) are dissolved in 500.0 mL of solution, what is the concentration of CH₃OH in the solution?
B) 2.18 M
Which of the following quantities is equivalent to 3.7 cm?
B) 3.7×10⁻⁵ km
How many significant figures would this calculation have if it were completed: (9.04 - 8.23 + 21.954 + 81.0) × 3.1416
B) 4
Glucose is an important biological molecule with the molecular formula C₆H₁₂O₆. What is its empirical formula?
B) CH₂O
What is the correct formula for cobalt(III) hydroxide?
B) Co(OH)₃
Methylene chloride (dichloromethane, CH₂Cl₂) was once a common ingredient in many paint strippers. Based on its molecular formula, what kind of bonding does this compound exhibit?
B) Covalent only
A compound that contains only carbon, hydrogen, and oxygen is 58.8% C and 9.87% H by mass. What is the empirical formula of this substance?
B) C₅H₁₀O₂
Which has the incorrect name-formula combination?
B) Iron(II) chlorate - FeClO₄
Which one of the following is an example of an element?
B) nickel
Which one of the following is an example of a compound?
B) water
Complete the balanced dissociation equation for the compound below in aqueous solution. If the compound does not dissociate, write NR after the reaction arrow.
Ba(ClO₄)₂(aq) + RbOH(aq) → NR
Complete the balanced dissociation equation for the compound below in aqueous solution. If the compound does not dissociate, write NR after the reaction arrow.
Ba(NO₃)₂(aq) + K₂SO₄(aq) → BaSO₄(s) + 2 KNO₃(aq)
Which one of the following represents the net ionic equation for the reaction of Ca(NO₃)₂ with Li₃PO₄?
C) 3 Ca²⁺ (aq) + 2 PO₄³⁻ (aq) → Ca₃(PO₄)₂ (s)
Perform this mathematical operation and express the answer to the correct number of significant figures: 185,007 ÷ 5301
C) 34.90
How many significant figures does the number 48.050 have?
C) 5
Which one of the following is the smallest mass?
C) 5.2 mg
Which of the following metric prefixes corresponds to 10⁶?
C) mega-
Rutherford's gold foil experiment determined that
C) most of the space in an atom is empty except for a concentrated area called the nucleus.
Balance the following chemical equation (if necessary) for the combustion reaction of glucose:
C₆H₁₂O₆(s) + 6O₂(g) → 6CO₂(g) + 6H₂O(g)
What is the mass percentage of O in C₃H₈O₂?
D) 42.06%
Which one of the following represents the net ionic equation for the reaction of AgNO₃ and LiBr?
D) Ag⁺ (aq) + Br⁻ (aq) → AgBr (s)
Which postulate(s) of Dalton's atomic theory of matter is/are NOT true?
D) Both (A) and (B) ∙ All atoms of a given element are identical. ∙ Atoms are indestructible.
Write the chemical formula for hydrobromic acid
HBr
Write the chemical formula for hypobromous acid
HBrO
Complete the balanced neutralization equation for the reaction below:
HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l)
Write the formula for perchloric acid
HClO₄
Complete the balanced dissociation equation for the compound below in aqueous solution. If the compound does not dissociate, write NR after the reaction arrow.
HClO₄(aq) → H⁺(aq) + ClO₄⁻(aq)
Write the formula for sulfurous acid
H₂SO₃
What is the correct IUPAC name for Cl₂O₇?
dichlorine heptoxide
Write the balanced NET ionic equation for the reaction when FeSO₄ and Ba(OH)₂ are mixed in aqueous solution. If no reaction occurs, simply write only NR.
Fe²⁺(aq) + SO₄²⁻(aq) + Ba²⁺(aq) + 2 OH⁻(aq) → Fe(OH)₂(s) + BaSO₄(s)
What is the correct IUPAC name for Mg₃P₂?
magnesium phosphide
What is the correct IUPAC name for HNO₃(aq)?
nitric acid
What is the correct IUPAC name for NI₃?
nitrogen triiodide
What is the correct IUPAC name for Ag₂S?
silver sulfide
What is the correct IUPAC name for Na₂SO₃?
sodium sulfite
What is the concentration of sodium ions in 0.185 M Na₂CO₃?
0.370 M
Kelvin is the SI unit for which physical quantity?
D) temperature
An unknown compound is processed using elemental analysis and found to contain 117.4 g of platinum, 28.91 g of carbon, and 33.71 g of nitrogen. How many moles of platinum are present in the compound?
0.6017 mol
What is the coefficient in front of the O₂ when the equation below is balanced (using only whole numbers and the lowest whole number ratio)? C₂H₄(g) + O₂ (g) → CO₂(g) + H₂O (g)
3
Write the balanced NET ionic equation for the reaction when CaBr₂ and Na₃PO₄ are mixed in aqueous solution. If no reaction occurs, simply write only NR.
3 Ca²⁺(aq) + 2 PO₄³⁻(aq) → Ca₃(PO₄)₂(s)
What is the correct IUPAC name for Ca(BrO₂)₂?
calcium bromite
What is the correct IUPAC name for CBr₄?
carbon tetrabromide
What is the correct IUPAC name for Cr₂O₃?
chromium(III) oxide
Complete the balanced dissociation equation for the compound below in aqueous solution. If the compound does not dissociate, write NR after the reaction arrow.
C₆H₈O₂(l) → NR
The answer to the calculation below with the correct number of significant figures is
D) 225.5
Which of the following is a pure substance that can be broken down into simpler substances by chemical means?
D) compound
What type of property is heat?
D) extensive physical property
A human is an example of a(n)
D) heterogeneous mixture
Which one of these represents a CHEMICAL change?
D) milk turns sour after sitting at room temperature for a few days
Write the balanced COMPLETE ionic equation for the reaction when calcium chloride and lithium bromide are mixed in aqueous solution. If no reaction occurs, simply write only NR.
NR
Write the balanced NET ionic equation for the reaction when HClO₄ and HI are mixed in aqueous solution. If no reaction occurs, simply write only NR.
NR
If 30.7 g of CH₃OH (MM = 32.04 g/mol) are added to a 500.0 mL volumetric flask, and water is added to fill the flask, what is the concentration of CH₃OH in the resulting solution?
1.92 M
An unknown element X has the following isotopes: ⁵²X (83.50% abundant), ⁴⁹X (8.00% abundant), ⁵⁰X (8.50% abundant). What is the average atomic mass in amu of X?
51.6 amu
Glucose is an example of a(n)
B) compound
Write the chemical formula for the hypobromite ion
BrO⁻
The number 0.00000620 written in scientific notation would be
C) 6.20 × 10⁻⁶
Which of the following best defines a scientific law?
C) A unifying concept; often a mathematical description of the way in which a natural phenomenon occurs
A chemist is trying to identify an unknown metal, and finds that 25.0 cm³ of the substance has a mass of 224.43 g at 20°C. Which of the following metals is it?
C) Copper, d = 8.98 g/cm³
A molecule has an empirical formula of CH, and its molar mass is known to be 26 g/mol. What is its molecular formula?
C) C₂H₂
Which of the following describes a chemical change involving water?
C) H₂O(l) → H₂(g) + ½O₂(g)
Which scientist determined the charge of the electron?
C) Robert Millikan
Which of the following states of matter is pictured below?
C) gas
Which of the following terms describes what a doctor forms when treating patients prior to ordering medical tests?
C) hypothesis
Complete the balanced dissociation equation for the compound below in aqueous solution. If the compound does not dissociate, write NR after the reaction arrow.
K₂SO₄(aq) + FeCl₃(aq) → NR