Introductory Chemistry Fourth Edition Nivaldo J. Tro Chapter 6 Chemical Composition Dr. Sylvia Esjornson Southwestern Oklahoma State University. Full file at musicmarkup.info Tro-Test-Bank Introductory Chemistry, 5e (Tro) Chapter 2 Measurement and. Introductory Chemistry PDF eBook, Global Edition, 5/E. View larger cover Introductory Chemistry with MasteringChemistry, Global Edition, 5/E. Tro. ISBN-
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Introductory. chemIstry. Fifth edition. Westmont college nivaldo J. tro All the art from the text, including figures and tables in JPG and PDF formats; movies. Tro's "Introductory Chemistry",. Chapter 3. 2. Matter. • Matter is anything that occupies space and has mass. • Even though it appears to be smooth and. PDF Introductory Chemistry (5th Edition) (Standalone Book) Author Nivaldo Tro draws upon his classroom experience as an award- winning.
Tro Chapter 6 Chemical Composition Dr. Sodium is an important dietary mineral that we eat in our food, primarily as sodium chloride table salt. Sodium is involved in the regulation of body fluids, and eating too much of it can lead to high blood pressure. The FDA recommends a person consume less than 2. The mass of sodium that we eat is not the same as the mass of sodium chloride that we eat. How many grams of sodium chloride can we consume and still stay below the FDA recommendation for sodium? The chemical composition of sodium chloride is given in its formula, NaCl.
We need a larger number because atoms are so small. The chemist s dozen is called the mole mol. This number is called Avogadro s number, named after Amadeo Avogadro. One mole of marbles corresponds to marbles. One mole of sand grains corresponds to sand grains. Twenty-two real copper pennies contain about 1 mol of copper Cu atoms. Two large helium balloons contain approximately 1 mol of helium He atoms. The numerical value of the mole is defined as being equal to the number of atoms in exactly 12 g of pure carbon This definition of the mole establishes a relationship between mass grams of carbon and number of atoms Avogadro s number.
This relationship allows us to count atoms by weighing them. Convert 3. Convert 1. The weight of one dozen nails changes for different nails. The weight of one mole of atoms changes for different elements. The molar mass of any element the mass of 1 mol of atoms of that element is equal to the atomic mass of that element expressed in atomic mass units. One copper atom has an atomic mass of amu.
The molar mass of copper is The mass of 1 mol of atoms changes for different elements: The lighter the atom, the less mass in one mole of that atom. Calculate the mass of aluminum g in 6. How many aluminum atoms are in an aluminum can with a mass of For compounds, the molar mass is the mass of 1 mol of molecules or formula units of that compound. Ionic compounds do not contain individual molecules. We convert between the mass of a compound and moles of the compound, then we calculate the number of molecules or formula units from moles.
The formula mass for a compound is the sum of the atomic masses of all of the atoms in a chemical formula. The formula mass of CO 2 is found: The molar mass of CO 2 is:. Calculate the mass in grams of 1. What is the mass of 4. How many leaves on 14 clovers? We write this as: Find the number of moles of O in 1. CFCs are chemically inert molecules used primarily as refrigerants and industrial solvents. In the upper atmosphere, sunlight breaks bonds within CFCs, resulting in the release of chlorine atoms.
The chlorine atoms react with ozone and destroy it by converting it from O 3 into O 2. The thinning of ozone over populated areas is dangerous because ultraviolet light can harm living things and induce skin cancer in humans. Most developed nations banned the production of CFCs on January 1, CFCs still lurk in older refrigerators and air conditioning units and can leak into the atmosphere and destroy ozone.
Antarctic ozone levels in three Septembers from to The darkest blue colors indicate the lowest ozone levels. The mass percent chlorine changes from one type of chlorofluorocarbon to another. The mass percent of chromium is:. This can be written as:. This can be written in fractional form: These fractions are conversion factors between g Na and g NaCl. How many grams of sodium chloride can you consume and still be within the FDA guidelines? Calculate the mass percent of Cl in C 2 Cl 4 F 2, freon Too much fluoride can cause teeth to become brown and spotted, a condition known as dental fluorosis.
Extremely high levels can lead to skeletal fluorosis. Adults who drink between 1 and 2 L of water per day would receive the beneficial amounts of fluoride from the water. What is the mass percent composition of F in NaF? How many grams of NaF should be added to L of water to fluoridate it at a level of 1. Yes, but it is the empirical formula, not the molecular formula. An empirical formula only gives the smallest whole-number ratio of each type of atom in a compound, not the specific number of each type of atom in a molecule.
The molecular formula is always a whole-number multiple of the empirical formula. For example, the molecular formula for hydrogen peroxide is H 2 O 2 and its empirical formula is HO. Decomposition of Water We decompose a sample of water in the laboratory and find that it produces 3. How do we determine an empirical formula from these data? Decomposition of Water to 3.
How many moles of each element formed during the decomposition of water? Divide the experimental mass of each element by the molar mass of that element. There are 3 mol of H for every 1. Write a pseudo-formula for water: To get whole-number subscripts in our formula, divide all the subscripts by the smallest one, in this case, 1.
Our empirical formula for water, which in this case also happens to be the molecular formula, is H 2 O. Write down or calculate as given the masses of each element present in a sample of the compound. If you are given mass percent composition, assume a g sample and calculate the masses of each element from the given percentages. Convert each of the masses in Step 1 to moles by using the appropriate molar mass for each element as a conversion factor.
Write down a pseudo-formula for the compound, using the moles of each element from Step 2 as subscripts. Divide all the subscripts in the formula by the smallest subscript. If the subscripts are not whole numbers, multiply all the subscripts by a small whole number see the following table to arrive at whole-number subscripts.
What is the empirical formula of the metal oxide? You are given the mass of the initial Ti sample and the mass of its oxide after the sample reacts with oxygen.
The difference is the mass of oxygen that combined with the titanium. The difference is the mass of oxygen. We need to find n in the expression: The molecular formula is a whole-number multiple of CH 2 O.
Fructose For fructose, the empirical formula molar mass is: Therefore, n is: We can then use this value of n to find the molecular formula.
Multiply the subscripts in the empirical formula by n to arrive at the molecular formula. The mole is a specific number 6. One mole of any element has a mass equivalent to its atomic mass in grams.
One mole of any compound has a mass equivalent to its formula mass in grams. The mass of 1 mol of an element or compound is its molar mass. Chemical formulas indicate the relative number of each kind of element in a compound.
These numbers are based on atoms or moles. By using molar masses, the information in a chemical formula can be used to determine the relative masses of each kind of element in a compound. The total mass of a sample of a compound can be related to the masses of the constituent elements contained in the compound.
We can refer to the relative masses of each kind of element within a compound to determine the empirical formula of the compound. If the chemist also knows the molar mass of the compound, he or she can also determine its molecular formula.
In order to relate the mass and number of. Mass and Moles of Substance A. Molecular Mass and Formula Mass. Section 3. Just as we can talk about mass of one atom of. Chapter 4 Chemical Composition Chapter 4 Topics 1. Mole Quantities 2. Moles, Masses, and Particles 3. Determining Empirical Formulas 4. Sum of the atomic Weights.
Example Exercise 9. State the mass of Avogadro s number of atoms for each of.
What is the Mole? A formula that gives only the simplest ratio of the relative number of atoms in a compound. Chapter 3: Stoichiometry Key Skills: Balance chemical equations Predict the products of simple combination, decomposition, and combustion reactions.
Calculate formula weights Convert grams to moles and. It also teaches you how to calculate. How much does a single atom weigh? Different elements weigh different amounts related to what makes them unique.
What units do we use to define the weight of an atom? The number of atoms in a mole of any pure substance. How do we go from the atomic scale to the scale of everyday measurements macroscopic scale? The gateway is the mole! But before we get to the. Chapter 3. The meaning and usefulness of the mole The mole or mol represents a certain number of objects. SI def.: All rights reserved. Matter Atomic weight, Molecular weight and Mole Atomic Mass Unit Chemists of the nineteenth century realized that, in order to measure the mass of an atomic particle, it was useless to use the standard.
The Mole Concept Ron Robertson r2 c: From mass spectrometry: Using Chemical Formulas Objective 1: Calculate the formula mass or molar mass of any given compound. The Formula Mass of any molecule, formula unit, or ion is the sum of the average atomic masses of all.
Chapter 3 Stoichiometry Chapter 3 Stoichiometry In This Chapter As you have learned in previous chapters, much of chemistry involves using macroscopic measurements to deduce what happens between atoms. Page 1 of 14 Amount of Substance Key terms in this chapter are: Moles I. Rice Counting II. Counting atoms and molecules I. When doing reactions chemists need to count atoms and molecules. The problem of actually counting individual atoms and molecules comes from. How do we figure this out?
We know that: The mole, Avogadro s number and molar mass of an element. Molecular mass molecular weight 3. Percent composition of compounds 4. Empirical and Molecular formulas. Contents Getting the most from this book On a microscopic level, two molecules of H 2 react with one molecule. The Mole Mole SI unit of measurement that measures the amount of substance. A substance exists as representa9ve par9cles.
Representa9ve par9cles can be atoms, molecules,. Chem 31 Fall Chapter 3 Stoichiometry: Write Equation in Words -you cannot write an equation unless you. The Mole Chapter 10 1 Objectives Use the mole and molar mass to make conversions among moles, mass, and number of particles Determine the percent composition of the components of a compound Calculate empirical.
C 2 H 6, 2 atoms of carbon combine with 6 atoms of.
A dozen Molar Mass Science 10 is a number of objects. A dozen eggs, a dozen cars, and a dozen people are all 12 objects. But a dozen cars has a much greater mass than a dozen eggs because the mass of each. Chemistry Post-Enrolment Worksheet The purpose of this worksheet is to get you to recap some of the fundamental concepts that you studied at GCSE and introduce some of the concepts that will be part.
Like a recipe: Relative atomic masses of. Sample Exercise 3. An atom of bromine has a mass about four times greater than that of an atom of neon. Which choice makes the correct comparison of the relative.
Formula Masses Ch 6. Percent Composition supplemental material 3. Chapter 1: Moles and equations 1 Learning outcomes you should be able to: Lecture 5, The Mole What is a mole? Moles Atomic mass unit and the mole amu definition: The atomic mass unit is defined this way. Lecture 3: The mass of a mole of atoms and the mass of a mole of molecules The composition of. A small pin contains 0. How many atoms of iron are in the pin?
A sample. A positively charged particle in the nucleus Atomic Number: We differentiate all elements by their number.
Avogadro s umber n 8, the talian scientist, Amadeo Avogadro proposed that: Equal volumes of gas at equal temperatures and pressures have the same number of particles. This law,. CH3 Stoichiometry The violent chemical reaction of bromine and phosphorus. Which of the following correctly represents g of water? Chapter 2 The Mole Note to teacher: You will notice that there are two different formats for the Sample Problems in the student textbook.
Where appropriate, the Sample Problem contains the full set of. Single Date: Kinetic Theory of Gases Homework: Read In these problems look for two things: Calculations and Chemical Equations Atomic mass: Mass of an atom of an element, expressed in atomic mass units Atomic mass unit amu: Average mass of all isotopes of a given.
A kilogram B ampere C candela. Chapter 1 The Atomic Nature of Matter 6. Substances that cannot be decomposed into two or more simpler substances by chemical means are called a. When the following equation is balanced, the coefficient of Al is. Al OH. Tuesday, November 27, Expectations: Chemistry Final Study Guide Multiple Choice Identify the choice that best completes the statement or answers the question.
Boiling is a physical change. When water boils, it turns into a gas, but the water molecules are the same in both the liquid water and the gaseous steam. When ice melts, it looks different but its composition is the same. Solid ice and liquid water are both composed of water molecules, so melting is a physical change. In a chemical change, matter does change its composition. For example, copper turns green upon continued exposure to air because it reacts with gases in air to form new compounds.
This is a chemical change. Rusting is a chemical change. When iron rusts, it turns from iron to iron oxide. In a chemical reaction, the substances present before the chemical change are called reactants. The substances present after the change are called products.
In physical changes, the atoms that compose the matter do not change their fundamental associations, even though the matter may change its appearance. In chemical changes, atoms do change their fundamental associations, resulting in matter with a new identity. A physical change results in a different form of the same substance. A chemical change results in a completely new substance. The liquid butane vaporizes to gaseous butane. The liquid butane and the gaseous butane are both composed of butane molecules; this is a physical change.
Produce a flame. The butane molecules react with oxygen molecules in air to form new molecules, carbon dioxide and water. In a nuclear reaction, significant changes in mass can occur. In chemical reactions, however, the changes in mass are so minute that they can be ignored.
During physical and chemical changes, the total amount of matter remains constant. It will react with g of oxygen to form g of carbon dioxide and 90 g of water. Energy is the capacity to do work.
Work is defined as the result of a force acting on a distance. The behavior of matter is driven by energy. Understanding energy is critical to understanding chemistry. The law of conservation of energy states that energy is neither created nor destroyed.
The total amount of energy is constant. Energy can be changed from one form to another. Energy can be transferred from one object to another. Energy cannot be created out of nothing, and it does not vanish into nothing. The total energy of a sample of matter is the sum of its kinetic energy, the energy associated with its motion, and its potential energy, the energy associated with its position or composition.
Electrical energy: The energy associated with the flow of electrical charge. Thermal energy: The energy associated with the random motions of atoms and molecules in matter. Chemical energy: A form of potential energy associated with the positions of the particles that compose a chemical system.
A second unit of energy is the calorie cal , the amount of energy required to raise the temperature of 1 g of water by 1 degree Celsius. A calorie is a larger unit than a joule: A related energy unit is the nutritional or capital C Calorie Cal , equivalent to little c calories. The average cost of residential electricity in the U.
How many joules does it contain?
Objects or systems with high potential energy tend to be unstable. Some chemical substances, such as the molecules that compose TNT trinitrotoluene , have a relatively high potential energy energy is concentrated in them. TNT molecules tend to undergo rapid chemical changes that lower their potential energy, which is why TNT is explosive. The temperature of a substance is a measure of its thermal energy. The hotter an object, the greater the random motion of the atoms and molecules that compose it, and the higher its temperature.
Heat, which has units of energy, is the transfer or exchange of thermal energy caused by a temperature difference. For example, when a piece of cold ice is dropped into a cup of warm water, heat thermal energy is transferred from the water to the ice.
Temperature, by contrast, is a measure of the thermal energy of matter not the exchange of thermal energy.
The Fahrenheit scale assigns 0 F to the freezing point of a concentrated saltwater solution and 96 F to normal body temperature. On the Fahrenheit F scale, water freezes at 32 F and boils at F. Room temperature is approximately 72 F. On the Celsius C scale scale, water freezes at 0 C and boils at C. Room temperature is approximately 22 C. The Kelvin K scale avoids negative temperatures by assigning 0 K to the coldest temperature possible, absolute zero. Absolute zero is the temperature at which molecular motion virtually stops.
The Celsius degree and the Kelvin degree are the same size. This table is useful when solving homework problems. C is the specific heat capacity in joules per gram per degree Celsius. T is the temperature change in Celsius. If you hold gallium in your hand, it melts from your body heat. How much heat must 2. Given: 2. An additional J would be needed to melt 2. Matter can exist as a solid, liquid, or gas.
Solid matter can be either amorphous or crystalline.