Solubility and Particle Attractions
By now, you are probably very familiar with the process of dissolving. You already know what it looks like when a solid dissolves in a liquid. Why, however, does something dissolve What is happening at the molecular level The reasons why a solute may or may not dissolve in a solvent are related to the forces of attraction between the solute and solvent particles. These forces include the attractions between two solute particles, the attractions between two solvent particles, and the attractions...
Single Displacement Reactions
In a single displacement reaction, one element in a compound is displaced or replaced by another element. Two general reactions represent two different types of single displacement reactions. One type involves a metal replacing a metal cation in a compound, as follows A BC AC B For example, Znw Fe NO3 2 aq Zn NO3 2 aq Fe2 s The second type of single displacement reaction involves a non-metal usually a halogen replacing an anion in a compound, as follows DE F DF E For example, Cl2 g CaBr2 aq gt...
Practice Problems Qls
14. Use the periodic table to predict the most common valences of the atoms in Groups 16 VIA and 17 VIIA . 15. If you had to assign a valence to the noble gases, what would it be The smaller atoms of elements in the first two periods usually have only one common valence, which is easily determined from the periodic table. Many larger elements, however, have more than one valence because the electron distribution in these elements is much more complex. Therefore, you will have to memorize the...
Practice Problems Dkt
34. The following reaction proceeds with a 70 yield. CeHam HNO3 aq C6H NO2W H2OW Calculate the mass of C6H5NO2 expected if 12.8 g of C6H6 reacts with excess HNO3. 35. The reaction of toluene, C7H8, with potassium permanganate, KMnO4, gives less than a 100 yield. C7H8M 2KMnO4 aq KC7H5O2 aq 2MnO2 s KOH aq H2OM a 8.60 g of C7H8 is reacted with excess KMnO4. What is the theoretical yield, in grams, of KC7H5O2 b If the percentage yield is 70.0 , what mass of KC7H5O2 can be expected c What mass of...
Practice Problems Meu
5. Copy each skeleton equation into your notebook, and balance it. a S s O2 g SO2 g c H2 g Cl2 g HCl g b P4 s O2 g P4O10H d SO2 g H2O H2SO3 aq 6. Indicate whether these equations are balanced. If they are not, balance them. a 4Fe s 3O2 g 2Fe2O3 s c H2O2 aq 2H2O O2 g d 2HCl aq Na2SO3 aq 2NaCl aq H2OW SO2 g Steps for Balancing Chemical Equations More complex chemical equations than the ones you have already tried can be balanced by using a combination of inspection and trial and error. Here,...
Classifying Matter and Its Changes
Matter is constantly changing. Plants grow by converting matter from the soil and air into matter they can use. Water falls from the sky, evaporates, and condenses again to form liquid water in a never-ending cycle. You can probably suggest many more examples of matter changing. Matter changes in response to changes in energy. Adding energy to matter or removing energy from matter results in a change. Figure 1.9 shows a familiar example of a change involving matter and energy. Like all matter,...
Determining the Empirical Formula of Magnesium Oxide
When magnesium metal is heated over a flame, it reacts with oxygen in the air to form magnesium oxide, MgxOy In this investigation, you will react a strip of pure magnesium metal with oxygen, O2, in the air to form magnesium oxide. Then you will measure the mass of the magnesium oxide produced to determine the percentage composition of magnesium oxide. You will use this percentage composition to calculate the empirical formula of magnesium oxide. QUQQOD Do not perform this investigation unless...
Dr Jiangning Wu Cleaning the Worlds Water
Around the world, researchers are working to reduce the pollutants in our lakes, rivers, and ground water. Both industry and agriculture too often produce waste water that contains everything from animal droppings and excess fertilizer to artificial colours and other chemicals. Yet, without industry and agriculture, we would not have many of the modern comforts we expect and enjoy. Jiangning Wu was born and raised in Nanjing, China. She came to Canada to complete her studies in chemical...
Describing and Measuring Matter
As you can see in the photograph at the beginning of this chapter, water is the most striking feature of our planet. It is visible from space, giving Earth a vivid blue colour. You can observe water above, below, and at Earth's surface. Water is a component of every living thing, from the smallest bacterium to the largest mammal and the oldest tree. You drink it, cook with it, wash with it, skate on it, and swim in it. Legends and stories involving water have been a part of every culture in...
Calculating Molar Concentration
A saline solution contains 0.90 g oi sodium chloride, NaCl, dissolved in 100 mL of solution. What is the molar concentration of the solution You need to find the molar concentration of the solution in mol L. You know that 0.90 g of sodium chloride is dissolved in 100 mL of solution. Step 1 To find the amount in mol of sodium chloride, first determine its molar mass. Then divide the amount of sodium chloride in g by its molar mass in g mol . Step 2 Convert the volume of solution from mL to L...
Practice Problems Wrx
C 7.13 H 14.3 C1.00H2.01 CH2 7.13 7.13 9. A compound consists of 17.6 hydrogen and 82.4 nitrogen. Determine the empirical formula of the compound. 10. Find the empirical formula of a compound that is 46.3 lithium and 53.7 oxygen. 11. What is the empirical formula of a compound that is 15.9 boron and 84.1 fluorine 12. Determine the empirical formula of a compound made up of 52.51 chlorine and 47.48 sulfur. The fact that 2.01 was rounded to 2 in CH2 is fine. The percentage composition is often...
Review 1
Summarize this chapter in the format of your choice. Here are a few ideas to use as guidelines Identify the subatomic particles that make up atoms, as well as the theory that chemists use to explain the composition and behaviour of atoms. Use the periodic law to examine the structure and organization of the periodic table of the elements. Draw Lewis structures to model the arrangements of electrons in the outer energy levels of atoms. Identify periodic trends involving atomic size, ionization...
Section Review Lno
Q COD The average atomic mass of potassium is 39.1 u. Explain why no single atom of potassium has a mass of 39.1 u. Q O Naturally occurring magnesium exists as a mixture of three isotopes. These isotopes with their isotopic abundances and atomic masses are Mg-24 78.70 , 23.985 u , Mg-25 10.13 , 24.985 u , and Mg-26 11.17 , 25.983 u . Calculate the average atomic mass of magnesium. Q O Assume that an unknown element, X, exists naturally as three different isotopes. The average atomic mass of...
Review
Summarize this chapter in the format of your choice. Here are a few ideas to use as guidelines List possible interactions among science, technology, society, and the environment STSE . Give examples of physical and chemical properties. Make a table of common SI units. Think about measurement and uncertainty. When is a number exact Make up a list of values. Challenge your friends to identify the number of significant digits in each. Review the rules for significant digits when adding,...
Ionic or Covalent
Imagine that you are a chemist. A colleague has just carried out a series of tests on the following compounds ethanol You take the results home to organize and analyze them. Unfortunately your colleague labelled the tests by sample number and forgot to write down which compound corresponded to each sample number. You realize, however, that you can use the properties of the compounds to identify them. Then you can use the compounds' properties to decide whether they are ionic or covalent. 1....
Using Molar Concentration to Find Mass
At 20 C, a saturated solution of calcium sulfate, CaSO4, has a concentration of 0.0153 mol L. A student takes 65 mL of this solution and evaporates it. What mass in g is left in the evaporating dish You need to find the mass in g of the solute, calcium sulfate. The molar concentration is 0.0153 mol L. The volume of the solution is 65 mL. Step 1 Convert the volume from mL to L using the formula Volume in L Volume in mL x A 0 L Step 2 Rearrange the following formula to solve for the amount of...
The Molecular Formula of a Compound
Determining the identity of an unknown compound is important in all kinds of research. It can even be used to solve crimes. Forensic scientists specialize in analyzing evidence for criminal and legal cases. To understand why forensic scientists might need to find out the molecular formula of a compound, consider the following example. Suppose that a suspect in a theft investigation is a researcher in a biology laboratory. The suspect frequently works with formaldehyde, CH2O. Police officers...
Finding a Compounds Empirical Formula from Percentage Composition Part B
The percentage composition of a fuel is 81.7 carbon and 18.3 hydrogen. Find the empirical formula of the fuel. You need to determine the empirical formula of the fuel. You know the percentage composition of the fuel. You have access to a periodic table. Convert mass percent to mass, then to number of moles. Then find the lowest whole number ratio. Table 6.2 Converting Subscripts in Empirical Formulas Table 6.2 Converting Subscripts in Empirical Formulas You now have the empirical formula...
Section Review Ubd
O O B In a large syringe, 48 mL of ammonia gas at STP is compressed to 24 mL and 110 kPa. What must the new temperature of the gas be Explain the result in terms of kinetic molecular theory. Q O Design an investigation to test Dalton's law of partial pressure. Write a procedure and list the materials and equipment you need. Q Explain Dalton's law of partial pressure. Q ik w What are the main components of the atmosphere Q IMC Popcorn pops as the water in the kernel is vapourized. The building...
Section Review Krg
O What mass of potassium chloride, KCl, is used to make 25.0 mL of a solution with a concentration of 2.00 mol L O A solution is prepared by dissolving 42.5 g of silver nitrate, AgNO3 in a 1 L volumetric flask. What is the molar concentration of the solution Q O The solution of aqueous ammonia that is supplied to schools has a concentration of 14 mol L. Your class needs 3.0 L of a solution with a concentration of 0.10 mol L. a What procedure should your teacher follow to make up this solution b...
Determining the Formula of a Hydrate
A hydrate of barium hydroxide, Ba OH 2xH2O, is used to make barium salts and to prepare certain organic compounds. Since it reacts with CO2 from the air to yield barium carbonate, BaCO3, it must be stored in tightly stoppered bottles. a A 50.0 g sample of the hydrate contains 27.2 g of Ba OH 2. Calculate the percent, by mass, of water in Ba OH 2xH2O. b Find the value of x in Ba OH 2xH2O. a You need to calculate the percent, by mass, of water in the hydrate of barium hydroxide. b You need to...
Review Oal
Summarize this chapter in the format of your choice. Here are a few ideas to use as guidelines Describe the difference between a saturated and an unsaturated solution. Explain how you can predict whether a solute will dissolve in a solvent. What factors affect the rate of dissolving What factors affect solubility How does temperature affect the solubility of a solid, a liquid, and a gas Describe how particle attractions affect solubility. Explain how to plot a solubility curve. Write the...
Chemistry Bulletin Wtn
Chemical Amounts in Vitamin Supplements Vitamins and minerals micronutrients help to regulate your metabolism. They are the building blocks of blood and bone, and they maintain muscles and nerves. In Canada, a standard called Recommended Nutrient Intake RNI outlines the amounts of micronutrients that people should ingest each day. Eating a balanced diet is the best way to achieve your RNI. Sometimes, however, you may need to take multivitamin supplements when you are unable to attain your RNI...
Qualitative Analysis
In this investigation, you will apply your knowledge of chemical reactions and the general solubility guidelines to identify unknown ions. How can you identify ions in solution Read the entire Procedure. Can you predict the results of any steps Write your predictions in your notebook. Justify each prediction. 12-well or 24-well plate, or spot plate unknowns 4 dropper bottles labelled A, B, C, and D of solutions that include Na aq , Ag aq , Ca2 aq , and Cu2 aq reactants 2 labelled dropper...
Practice Problems Czx
16. Write a balanced formula for a compound that contains sulfur and each of the following elements. Use a valence of -2 for sulfur. 17. Write a balanced formula for a compound that contains calcium and each of the following elements. How do you write and balance formulas that contain polyatomic ions The same steps can be used, as long as you keep the atoms that belong to a polyatomic ion together. The easiest way to do this is to place brackets around the polyatomic ion at the beginning. For...
Practice Problems Whi
31. 20.0 g of bromic acid, HBrO3, is reacted with excess HBr. HBrO3 aq 5HBr aq 3H2OM 3Br2 aq a What is the theoretical yield of Br2 for this reaction b If 47.3 g of Br2 is produced, what is the percentage yield of Br2 32. Barium sulfate forms as a precipitate in the following reaction Ba NO3 2 aq Na2SO4 aq BaSO4 s 2NaNO3 aq When 35.0 g of Ba NO3 2 is reacted with excess Na2SO4, 29.8 g of BaSO4 is recovered by the chemist. a Calculate the theoretical yield of BaSO4. b Calculate the percentage...
Determining the Chemical Formula of a Hydrate
Many ionic compounds exist as hydrates. Often you can convert hydrates to anhydrous ionic compounds by heating them. Thus, hydrates are well suited to determining percentage composition experimentally. In this investigation, you will find the mass percent of water in a hydrate of copper II sulfate hydrate, CuSO4-xH2O.You will use copper II sulfate hydrate for an important reason The crystals of the hydrate are blue, while anhydrous copper II sulfate is white. What is the molecular formula of...
Finding Empirical and Molecular Formulas by Experiment
You have learned how to calculate the percentage composition of a compound using its formula. Often, however, the formula of a compound is not known. Chemists must determine the percentage composition and molar mass of an unknown compound through experimentation. Then they use this information to determine the molecular formula of the compound. Determining the molecular formula is an important step in understanding the properties of the compound and developing a way to synthesize it in a...
Practice Problems Ywl
27. Chloride dioxide, ClO2, is a reactive oxidizing agent. It is used to purify water. 6ClO2 g 3H2OW 5HClO3 aq HCl aq a If 71.00 g of ClO2 is mixed with 19.00 g of water, what is the limiting reactant b What mass of HClO3 is expected in part a c How many molecules of HCl are expected in part a You will use the concepts of stoichiometry and limiting reactants in the Chemistry Course Challenge. If you have two reactants and you want to use up all of one reactant, which is the limiting reactant...
Polar and NonPolar Substances
In the Thought Lab in section 8.1, you observed that solid iodine is insoluble in water. Only a weak attraction exists between the non-polar iodine molecules and the polar water molecules. On the other hand, the intermolecular forces between the water molecules are very strong. As a result, the water molecules remain attracted to each other rather than attracting the iodine molecules. You also observed that iodine is soluble in kerosene. Both iodine and kerosene are non-polar substances. The...
The Solubility of Ionic Compounds
In this investigation, you will work with a set of solutions. You will chemically combine small quantities, two at a time. This will help you determine which combinations react to produce a precipitate. A precipitate is an insoluble solid that may result when two aqueous solutions chemically react. The appearance of a precipitate indicates that an insoluble compound is present. Then you will compile your data with the data from other groups to develop some guidelines about the solubility of...
Inquiry Wik
6. A freshly exposed aluminum surface reacts with oxygen to form a tough coating of aluminum oxide. The aluminum oxide protects the metal from further corrosion. 4Al s 3O2 g 2Al2O3 s How many grams of oxygen are needed to react with 0.400 mol of aluminum 7. Calcium metal reacts with chlorine gas to produce calcium chloride. How many formula units of CaCl2 are expected from 5.3 g of calcium and excess chlorine 8. Propane is a gas at room temperature, but it exists as a liquid under pressure in a...
Section Review Sxf
Q K U In your own words, define the mole. Use three examples. Q O Imagine that 6.02 x 1023 were evenly distributed among six billion people. How much money would each person receive Q O A typical adult human heart beats an average of 60 times per minute. If you were allotted a mole of heartbeats, how long, in years, could you expect to live You may assume each year has 365 days. O Calculate the number of atoms in 3.45 mol of iron, Fe. 0 O A sample of carbon dioxide, CO2, contains 2.56 x 1024...
[jj The Effect of Temperature on Soda Water
In this Express Lab, you will have a chance to see how a change in temperature affects the dissolved gas in a solution. You will be looking at the pH of soda water. A low pH 1-6 indicates that the solution is acidic. You will learn more about pH in Chapter 10. If using a hot plate, avoid touching it when it is hot. If using a Bunsen burner, check that there are no flammable solvents nearby. 1. Open a can of cool soda water. Listen for the sound of excess carbon dioxide escaping. Pour about 50...
Modelling Mole and Mass Relationships
Chemists use the mole to group large numbers of atoms and molecules into manageable, macroscopic quantities. In this way, they can tell how many atoms or molecules are in a given sample, even though the particles are too small to see. In this investigation, you will explore how to apply this idea to everyday objects such as grains of rice and nuts and bolts. How can you use what you know about the mole and molar mass to count large numbers of tiny objects using mass, and to relate numbers of...
Practice Problems Qgm
5. Hydrogen is found primarily as two isotopes in nature 1H 1.0078 u and H 2.0140 u . Calculate the percentage abundance of each isotope based on hydrogen's average atomic mass. 6. Lanthanum is composed of two isotopes 157La 137.91 u and 137La 138.91 u . Look at the periodic table. What can you say about the abundance of La 7. Rubidium ignites spontaneously when exposed to oxygen to form rubidium oxide, Rb2O. Rubidium exists as two isotopes 3fRb 84.91 u and 37Rb 86.91 u . If the average atomic...
Practice Problems Yim
8. Refer to the Sample Problem above. a How many moles of V are needed to produce 7.47 mol of VO2 Assume that sufficient O2 is present. b How many moles of V are needed to react with 5.39 mol of O2 to produce V2O3 9. Nitrogen, N2, can combine with oxygen, O2, to form several different oxides of nitrogen. These oxides include NO2, NO, and N2O. a How many moles of O2 are required to react with 9.35 x 10-2 moles of N2 to form N2O b How many moles of O2 are required to react with 9.35 x 10-2 moles...
Practice Problems Ulj
31. Calculate the number of moles in each sample. a 103 g of Mo c 0.736 kg of Cr b 1.32 x 104 g of Pd d 56.3 mg of Ge 32. How many moles of compound are in each sample a 39.2 g of silicon dioxide, SiO2 b 7.34 g of nitrous acid, HNO2 c 1.55 x 105 kg of carbon tetrafluoride, CF4 d 8.11 x 10-3 mg of 1-iodo-2,3-dimethylbenzene C8H9I 33. Sodium chloride, NaCl, can be used to melt snow. How many moles of sodium chloride are in a 10 kg bag 34. Octane, C8H18, is a principal ingredient of gasoline....
Observing Double Displacement Reactions
A double displacement reaction involves the exchange of cations between two ionic compounds, usually in aqueous solution. It can be represented with the general equation AB CD AD CB Most often, double displacement reactions result in the formation of a precipitate. However, some double displacement reactions result in the formation of an unstable compound which then decomposes to water and a gas. The reaction of an acid and a base a neutralization reaction is also a type of double displacement...
Estimating Concentration of an Unknown Solution
Copper II sulfate, CuSO4, is a soluble salt. It is sometimes added to pools and ponds to control the growth of fungi. Solutions of this salt are blue in colour. The intensity of the colour increases with increased concentration. In this investigation, you will prepare copper II sulfate solutions with known concentrations. Then you will estimate the concentration of an unknown solution by comparing its colour intensity with the colour intensities of the known solutions. Copper II sulfate...
From Copper to Copper
This experiment allows you to carry out the sequential conversion of copper metal to copper II nitrate to copper II hydroxide to copper II oxide to copper II sulfate and back to copper metal. This conversion is carried out using synthesis, decomposition, single displacement, and double displacement reactions. What type of chemical reaction is involved in each step of this investigation Examine the five reactions outlined in the procedure. Predict what reactions will occur, and write equations...
Solvents and Coffee Whats the Connection
The story of coffee starts with the coffee berry. First the pulp of the berry is removed. This leaves two beans, each containing 1 to 2 caffeine. The beans are soaked in water and natural enzymes to remove the outer parchment husk and to start a slight fermentation process. Once the beans have been fermented, they are dried and roasted. Then the coffee is ready for grinding. Grinding increases the surface area of the coffee. Thus, finer grinds make it easier to dissolve the coffee in hot water....
Calculating the Molar Mass of an Unknown Gas Teacher Demonstration
Cigarette lighters contain a gaseous fuel that burns quickly. It produces a large amount of heat using only a small amount of gas. Your teacher will measure the volume and mass of a sample of this gas. Then you will use these data to calculate the molar mass of the gas. Your teacher will take the following Safety Precautions and perform the following steps. Remember that this gas is flammable. Do not try to produce flames with the lighters. Before beginning, check that there are no flames such...
Practice Problems Atq
1. What is the concentration in percent m v of each solution a 14.2 g of potassium chloride, KCl used as a salt substitute , dissolved in 450 mL of solution b 31.5 g of calcium nitrate, Ca NO3 2 used to make explosives , dissolved in 1.80 L of solution c 1.72 g of potassium permanganate, KMnO4 used to bleach stone-washed blue jeans , dissolved in 60 mL of solution 2. A solution of hydrochloric acid was formed by dissolving 1.52 g of hydrogen chloride gas in enough water to make 24.1 mL of...