Chemistry Semester 1 Exam
What are the coefficients that would correctly balance this equation? ____Zn + ____K2CrO4 → ____K + ____ZnCrO4
1, 1, 2, 1
Calculate the number of molecules present in .20 moles of H2O.
1.2x10^23 molecules
The reactivity trends on the Periodic Table depends on valence electrons. What family on the Periodic Table is identified as the most reactive nonmetals?
17
What is percent composition of the element hydrogen in the compound methane, CH4?
25.1%
The reaction between solid aluminum and liquid bromine is exothermic. This reaction creates the product aluminum bromide. What equation includes the correct formulas and demonstrates conservation of mass?
2Al(s) + 3Br2(l) → 2AlBr3(s)
A list of the materials for a chemistry lab are provided. 1. A 3 cm long strip of magnesium 2. A 10 mL sample of hydrochloric acid 3. A stir rod with density greater than 1.5 g/mL 4. A beaker at room temperature Which materials are listed with intensive properties?
3 and 4
What is the percent composition, to two significant digits, for each element in sodium chloride (NaCl)?
39% Na, 61% Cl
Methane is natural gas containing both carbon and hydrogen. What type of reaction occurs when methane reacts with oxygen gas to produce carbon dioxide, water, and energy?
Combustion
What is the correct name for the following compound? H2O
Dihydrogen monoxide
The Lewis valence dot electron structures are used to illustrate the number of valence electrons of atoms of representative elements. Considering this, use the Periodic Table to predict the number of "dots" that should be drawn around Antimony (Sb) to represent its Lewis Dot Structure.
5
What is the molar mass of sodium chloride, NaCl?
58.44 g/mol
How many Mg atoms are found in 1.00 mole of MgO?
6.02x10^23
A sample of Element X is found to contain 72.15% of isotope type 1 (84.9118 amu) and 27.85% of isotope type 2 (86.9092 amu). Calculate the average atomic mass.
85.47 amu
Describe one chemical change and one physical change in a burning candle.
A chemical change is producing heat, and a physical change is melting wax in a burning candle.
Which of the following could represent a molecular formula for CH2O?
C6H12O6
Which of the following is a possible compound formed from Ca2+ and NO3-1?
Ca(NO3)2
What is an example of a pure substance?
Oxygen
Which of the following elements has the largest atomic radius?
Potassium
Metals can conduct electricity and heat well due to —
the ability of the electrons to move freely throughout the metal
Which statement best describes the name and location on the Periodic Table of the elements with the highest and lowest electronegativity, respectively?
Fluorine, on the upper right, has the highest electronegativity, and Francium, on the lower left, has the lowest electronegativity.
Substances with an indefinite shape and an indefinite volume are in which state of matter?
Gaseous state
What is the correct name for the following compound? Li2S
Lithium sulfide
Using the Periodic Table, predict which elements will have similar chemical properties or reactivity.
Magnesium, strontium, and barium
Which of the following statements is most accurate regarding atoms?
Atoms of the same element may have different mass numbers.
Which of the following is considered to be a chemical property of matter?
Reactivity
What is the chemical formula for disulfur decafluoride?
S2F10
Which of these statements describes the basic idea of the Valence Shell Electron Pair Repulsion (VSEPR) theory?
Shared and unshared electron pairs repel each other as much as possible.
Which of the following is considered to be a physical property of matter?
Solubility
Which of the following would not be classified as a pure substance?
Solution
Alkali metals react very readily with halogens and form ionic compounds such as table salt (NaCI) and many others. Which of the following explanations most completely describes why these two families of elements reacts readily?
The alkali metals have one valence electron, and the halogens are one short of an octet.
Visible light has a higher frequency than radio waves on the electromagnetic spectrum. How does the wavelength of visible light compare to radio waves?
Visible light has a shorter wavelength than radio waves.
What atom matches this electron configuration?1s22s22p63s23p64s23d10
Zinc
