Name: Period: Date: Types of Bonding Lab Inquiry

Transcription

1 Types of Bonding Lab Inquiry One of the most important jobs of a chemist is to relate the properties of observable amounts of substance to the properties on the atomic level which are less easily observed. Your Task: You will consider six different substances (aspirin, Epsom salt, copper, paraffin wax, table salt, and zinc) and group them according to their properties. After grouping them, you will examine what common characteristics can be found in how the compounds are put together. Pre-Lab Requirements: Write a hypothesis about which of the six substances will be grouped together at the completion of the lab. Hypothesis: Procedure Part A Appearance 1. Observe each compound using a magnifying glass. Record detailed observations about its shape (does it appear regular or irregular) in particular. Part B Melting Point 1. Take 6 small squares of aluminum foil and make a small bowl shape with each one. Be sure that your bowls will not leak when the compounds melt. 2. Place a small amount of sodium chloride, aspirin, Epsom salt, copper, zinc, and paraffin wax in its own aluminum foil bowl. Gently place all six bowls on a hot plate and heat them on a medium setting. The aspirin emits a strong-smelling vapor as it decomposes. Be careful not to inhale the vapors as you make your observations. 3. Observe what happens to each of the compounds. Be sure to record what order the compounds melt in. 4. Once a compound melts completely, take it off the hot plate using crucible tongs. After 8-10 minutes, remove any compounds that have not melted. 5. Once any compounds that melted have cooled down and frozen again, place all of the compounds and aluminum foil in the trash. Part C Conductivity and Solubility in Water 6. I will be providing data about the conductivity of each substance in water through a demonstration. Conductivity data is provided in µsiemens/meter. A higher conductivity reading indicates that a substance is a better electrical conductor. 7. To evaluate solubility of each compound, take a small beaker, partially fill with water. Add a small amount of the substance to the water. Stir with a stirring rod. After a minute or two, record your observations about whether the compound is soluble in water.

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3 Compound Name Aspirin Appearance (Regular or Irregular) Melting Order Conductivity in water (µs/m) Solubility in water (Soluble or insoluble) Formula Melting Point Epsom salt Copper Paraffin wax Table salt Zinc

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5 Part D Research 1. Each table group (4 people) will locate the formula and melting point for a group of compounds: a. paraffin wax, Epsom salt b. copper, sodium chloride c. zinc, aspirin, magnesium oxide d. calcium bromide, tungsten e. iron, calcium hydroxide f. octane, cobalt g. carbon tetrachloride, acetylene * Ask me how to find the information for these two* 2. The simplest way of doing this is to go to click Chemicals, and enter the name of the chemical in the Search for Chemicals box. This search will produce a list. Go down the list until you see an item that says View MSDS for (insert name of your chemical) and click on the link. 3. This will pull up the MSDS, or Material Safety Data Sheet for each item. Look for the information you need and record it on your data sheet and on Mrs. Atkins spreadsheet. 4. You will need to copy down the information for all of the compounds to use in your analysis questions. Compound Name Magnesium oxide Calcium bromide Tungsten Iron Calcium hydroxide Octane Cobalt Carbon tetrachloride Acetylene Formula Melting Point Analysis Questions: 1) Compare the chemical formulas for each of the compounds, including the ones looked up online, to their melting points. What patterns do you notice between these two?

6 2) Compare the formulas for each of the six compounds we evaluated in the lab to their abilities to conduct electricity in solution. What patterns do you notice between these two? 3) Compare the formulas for each of the six compounds we evaluated in the lab to their appearance and shape. What patterns do you notice between these two? 4) Group each of the six chemicals and the chemicals researched online based on the type of bonding found in each chemical. For each group, list the properties (appearance, melting point, conductivity in water, solubility in water) that are similar in the group.