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LAB 5-MASS to MOLE to MASS STOICHIOMETRY. OVERVIEW:
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LAB 5-MASS to MOLE to MASS STOICHIOMETRY • OVERVIEW: • At this time, your product is drying and therefore you cannot measure the EXPERIMENTAL or MEASURED mass in grams. The water would add mass and would cause you to overestimate the mass of your product, PbCr2O7(s). Please note water is not in the reaction, it is the solvent and does not interact chemically. You can however calculate your THEORETICAL YEILD, the mass of product you SHOULD have collected in your filter paper cone.
OVERVIEW CONTINUED: • The calculation is performed in three steps • CONVERT THE GIVEN OR KNOWN TO MOLES. • RATIO MOLES OF GIVEN TO MOLES OF OBJECTIVE. • CONVERT MOLES OF OBJECTIVE TO GRAMS, THEN COMPARE IT TO WHAT YOU ACTUALLY COLLECTED AND MEASURED IN LAB.
FLOWCHART OF THE THEORETICAL CALCULATION Step # 1 CONVERT REACTANT(KNOWN) TO MOLES MOLES KNOWN = MASS (GRAMS) MOLAR MASS Step #2 MOLE RATIO (FROM REACTION) KNOWN . COEFFICIENT KNOWN = MOLES KNOWN OBJECTIVE .COEFFICIENT OBJ. MOLES OBJ. (X) Step #3 CONVERT KNOWN REACTANT TO MOLES MOLES OBJ. = MASS (GRAMS) (X) MOLAR MASS
Step # 1 CONVERT KNOWN REACTANT Pb(NO3)2 TO MOLES MOLES KNOWN = MASS used = 1.13g = 0.0034 mol MOLAR MASS 331.15 g/mol Pb(NO3)2 Step #2 MOLE RATIO (COEFFICIENT, from reaction) KNOWN : = COEFFICIENT KNOWN = MOLES KNOWN OBJECTIVE: COEFFICIENT OBJ. MOLES OBJ. (X) Pb(NO3)2 = 1 = 0.0034 mol =X = 0.0034 PbCr2O7(s). 1 X mol Step # 1 CONVERT OBJECTIVE TO MASS IN GRAMS. MOLES OBJ. = MASS (GRAMS) = 0.0034 = X grams = 1.438g PbCr2O7 MOLAR MASS 423.11 g/mol
CALCULATION OF MOLAR MASS of K2Cr2O7 LIST SUBSCRIPTS MULTIPLY By atomic mass INSERT ATOMIC MASS FROM PERIODIC TABLE LIST ELEMENTS HERE 294.09 g/mol
CALCULATION OF MOLAR MASS of Pb(NO3)2 LIST SUBSCRIPTS MULTIPLY By atomic mass INSERT ATOMIC MASS FROM PERIODIC TABLE LIST ELEMENTS HERE The number of O atoms is 3times2 The number of N atoms is 1times 2 331.15 g/mol
CALCULATION OF MOLAR MASS of PbCr2O7 LIST SUBSCRIPTS MULTIPLY By atomic mass INSERT ATOMIC MASS FROM PERIODIC TABLE LIST ELEMENTS HERE The number of O atoms is 7 The number of Cr atoms is 2 423.11 g/mol