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Density and Molar Volume Molar Volume We have already investigated the relationship between mass, mole and the number of particles. But, is there any relationship between volume and mass, or mole and number of particles? Lets investigate. Purpose: Determine if there is a mathematical relationship between the mole and molar volume. Q1. If the molar mass (g/mole) is divided by the density (g/mL), what units remain? Q2. What would be an appropriate name for measurements having units in moles per mL? DIRECTIONS FOR TI-82/83 o Clear all equations Set up the Ö EDIT table with the following data: Construct a scatter plot of density versus molar mass L1=Molar Mass (g/mol) for the elements listed below. L2=Density (g/mL) y o Plots Off Plot1 ON " Xlist=L1 Ylist=L2 q ZoomStat Substance Molar Mass Density Al 27.0 g/mol 2.7 g/mL Fe 55.9 g/mol 7.9 g/mL Cu 63.5 g/mol 8.9 g/mL Zn 65.4 g/mol 7.1 g/mL Mo 95.4 g/mol 8.6 g/mL Zr 91.2 g/mol 4.5 g/mL Ag 107.9 g/mol 11.5 g/mL Ta 181 g/mol 13 g/mL Au 197.0 g/mol 19.3 g/mL Hg 200.6 g/mol 13.6 g/mL Sketch a simple diagram of the graph into your lab report. Q3. Does the data between molar mass and the density of the various metals seem to fit an easily recognized mathematical function? DIRECTIONS FOR TI-82/83 o Clear all equations Next, examine the following data for gases and Set up the Ö EDIT table with the following data: determine if there is a mathematical relationship L1=Density (g/mL) between the density of a gas and it’s molar mass. Do L2=Molar Mass (g/mol) this by constructing a scatter plot of molar mass vs. y o density. Plots Off Plot1 ON " Xlist=L1 Ylist=L2 q ZoomStat Substance Molar Mass Density Hydrogen 2.0 g/mol 0.089 g/L Hydrogen fluoride 20.0 g/mol 0.893 g/L Neon 20.19g/mol 0.901 g/L Ethane 30.0 g/mol 1.34 g/L Oxygen 32.0 g/mol 1.43 g/L Fluorine 39.0 g/mol 1.74 g/L Carbon dioxide 44.0 g/mol 1.96 g/L Sulfur dioxide 64.1 g/mol 2.86 g/L DIRECTIONS FOR TI-82/83 Calculate the line of best fits for the graph of Molar •TI-82 only Mass (g/mol) vs. Density (g/L) . Record the Ö CALC Setup 2VarStats Xlist L1 Ylist L2 regression equation in your lab note book and add the •TI-82/83 regression line to your graph. Ö CALC LinReg(ax+b) ENTER ENTER o Y1 ê Statistics EQ RegEQ s Sketch a simple diagram of the graph into your lab report and record the regression equation. Y= Answer the following questions in reference to the graph of molar mass and density. Q4. Is there a relationship between molar mass and density? Q5. Is it correct to assume a (0,0) origin for the graph ? Explain. Q6. What does the slope of the line represent? Q7. What is the numerical value (with label) for the slope of the line? Q8. If the molar mass is in grams per mole, then what might be an appropriate term for grams per liter? Q9. What are STP conditions? Q10. The molar volume is a constant value for gases kept at STP. Why would the temperature and pressure be important considerations in the volume of a gas? Q11. Scientists can count the particles of a solid or liquid by _____________ the sample. Scientists can count the particles of a gas by __________________ the volume of a gas at _____________________..
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