Concept explainers
In Section 2.1 it was pointed out that mass and energy are alternate aspects of a single entity called mass-energy. The relationship between these two physical quantities is Einstein’s famous equation, E = mc2, where E is energy, m is mass, and c is the
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Chemistry
- 3.83 For the reaction of nitrogen, N2, and hydrogen, H2, to form ammonia, NH3, a student is attempting to draw a particulate diagram, as shown below. Did the student draw a correct representation of the reaction? If not, what was the error the student made?arrow_forwardOn October 21, 1982, the Bureau of the Mint changed the composition of pennies (see Exercise 120). Instead of an alloy of 95% Cu and 5% Zn by mass, a core of 99.2% Zn and 0.8% Cu with a thin shell of copper was adopted. The overall composition of the new penny was 97.6% Zn and 2.4% Cu by mass. Does this account for the difference in mass among die pennies in Exercise 120? Assume the volume of the individual metals that make up each penny can be added together to give the overall volume of the penny, and assume each penny is the same size. (Density of Cu = 8.96 g/cm3; density of Zn = 7.14 g/cm3).arrow_forwardBromine (atomic mass 79.904 amu) consists of 2 different naturally occurring isotopes, Br-79 (atomic mass = 78.9193 amu) and Br-81 (80.9163 amu). If a student measures out 35.47 mL of Br2(l), which has a density = 3.119 g/mL), calculate the number of atoms of Br-81 in the given volume of bromine liquid.arrow_forward
- 19.78 mL of bromine contains 6.022 x 1023 bromine molecules. How many bromine atoms are in 3.00 L of bromine? (Each bromine molecule, Br2, contains two bromine atoms.)arrow_forwardThe density of gold metal is 19.3 g/cm3, while that for silver is 10.5 g/cm3. Suppose you had the same size bar of each metal, with the dimensions 2.00 in x 10.0 cm x 760 mm. Volume of a cube is height x length x width. Which bar would have the greatest mass? Which bar contains the greater number of atoms? If the two bars were melted and mixed together to form an alloy (or mixture) what would be the total mass?arrow_forwardMatter is neither created nor destroyed in a chemical reaction. Thus, the mass of the products of a chemical reaction must be equal to the mass of the starting materials. Formally, this concept is called the law of conservation of mass. When carbon is burned in air, it reacts with oxygen to form carbon dioxide. When 16.8 g g of carbon were burned in the presence of 59.1 g of oxygen, 14.3 g of oxygen remained unreacted. What mass of carbon dioxide was produced?arrow_forward
- The mass of a copper coin is 7.83 g. Suppose it were pure copper. a) How many moles of Cu atoms would the copper contain, given that the molar mass of Cu is 63.55 g/mol? The calculation has been set up for you. You must fill in the blanks with the correct values, including units. Round your answer to 3 significant figures. 7.83 g × (y) = (z) (x) = (y) = (z) = %3D b) How many Cu atoms are present? The calculate has been set up for you. You must fill in the blanks with the correct values, including units. Round your answer to 3 significant figures and use the exponent notation for Avogadro's number (i.e. 6.022E23 atoms). Note that (z) is the same value as above, so you don't need to fill it in again below. (m) (z) × (n) (p) (m) = (n) = (p) =arrow_forwardA college chemistry student is performing this reaction in a lab, where magnesium is burned and combines with oxygen from the air to produce magnesium oxide. The students burns 2.92 g of Mg, and there is excess oxygen from the air. They incorrectly 'culated that the mass of magnesium oxide produced was 2.42 g. Here is their work: 2.92 g 1 mol 2 mol 40.3 g = 2.42 g 1 24.3 g 1 mol 1 mol 1) What did the student do wrong? There is an error in their work. Explain specifically what part is incorrect. 2) What recommendation(s) would you give to the student regarding showing their work? There is an improvement that can be made to help them avoid this mistake in the future. pts) 3) Instead of 2.42 g, what answer should the student have gotten?arrow_forwardGiven that 6.02 x 1023 ethanol molecules have a mass of 46.04 g, calculate the number of ethanol molecules in a film of ethanol that is 3.08 mm by 10.0 cm by 0.0015 mm. Assume the density of ethanol is 0.790 g/mL.arrow_forward
- The density of Neon (Ne) at a specific temperature and pressure is 3.21 x 10-5 lb/in3. Calculate the volume of 1.2 x 108 Ne atoms, in cm3, under these conditions. 1000 lb = 453.6 g 1 inch = 2.54 cmarrow_forwardA 0.400-g sample of Niobium(IV) oxide is reacted with oxygen gas, yielding 0.4256 g of a new compound, NbxOy. Write a balanced chemical equation for this reaction (include state symbols to indicate whether each compound is solid, gas, liquid, etc.). You may write your coefficients in terms of x and y. What is the molecular formula of the new compound (that is, what are the values of x and y)?arrow_forwardEarth’s surface area is 5.1 x 108 km2, its crust has an average thickness of 35 km and an average density of 2.8 g/cm3. The two rarest (non-radioactive) elements in the crust are ruthenium and rhodium, each with an abundance of 1.0 x 10-4g/metric ton crust. What is the total mass of these two elements in the earth’s crust? (1g = 1 x 10-6 metric ton)arrow_forward
- Chemistry: The Molecular ScienceChemistryISBN:9781285199047Author:John W. Moore, Conrad L. StanitskiPublisher:Cengage LearningChemistryChemistryISBN:9781305957404Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCostePublisher:Cengage Learning
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