Moles, Molecules, and Chemical ReactionsCatherine Lozier01/29/2013Chem 1310 Section C02TA Ryan BucherLab Partners:Chelsey Arnold Sunya MorinTran GHonor Pledge: I did not copy this work from any others student(s), current students in lab or old lab reports ________________________________________________SignatureDATA AND OBSERVATIONSPart IUnknown Sample: GBefore Heating After HeatingMass crucible +lid (g) 22.031 g 1st Mass crucible, lid, sample (g) 22.268 gMass crucible +lid + sample (g) 22.438 g 2nd Mass crucible, lid , sample (g) 22.261 gMass sample, before heating (g) 0.407 g 3rd Mass crucible, lid , sample (g) 22.252 gMass anhydrous sample (g) 0.221 gPart IICompounds Solubility Observations Soluble (S) or Insoluble (I)NaCl Dissolved quickly SKNO3Dissolved quickly SAgNO3Dissolved quickly SCaCO3Turned milky, appeared to dissolve then settled out INa2CO3Dissolved slowly SPb(NO3)2Dissolved SCuSO4·5H2O Dissolved SCaSO4·2H2O Milky ICH3COONa Dissolved SNaHCO3Dissolved SBaSO4Partially dissolved, milky IKI Dissolved SReactions ObservationsNaCl(aq) + AgNO3(aq) White precipateNaCl(aq) + KNO3(aq) No observed reactionCuSO4(aq) + NaOH(aq) Cloudy, blue particlesHCl(aq) + Na2CO3(aq) pH: HCl = 1, Na2CO3 = 11, final = 9AgNO3(aq) + KI(aq) Yellow particlesNaOH(aq) + HCl(aq) pH: NaOH = 12, HCl = 1, final = 6Pb(NO3)2(aq) + KI(aq) Bright yellow liquidCH3COONa (aq) + AgNO3(aq) pH: CH3COONa = 7, AgNO3 = 6, final = 6CH3COOH (aq) + KOH(aq) pH: CH3COOH = 3, KOH = 11, final = 6NH4OH(aq) + H2SO4(aq) pH: NH4OH = 8, H2SO4 = 1, final = 2DISCUSSIONPart IThe purpose of Part I was to determine an unknown substance based on the water content of the hydrated sample. The mass of water in the unknown sample G was calculated to be 0.186 grams, which is approximately 45.7% of the mass of the hydrated sample. Based on this ratio of water to salt mass, the unknown sample is most similar to melanterite which has a water mass ratio of 45.36%; however, melanterite is characteristically a green mineral whereas the unknown substance was white. This would indicate that the sample was actually goslarite, which has a similar water mass ratio of 43.86%, but is a white crystal. Based on the observed physical properties andthe water mass ratio, it is likely that the unknown sample is goslarite, and that there were several sources of error in the experiment.There are several sources of error that could skew the data towards a higher water mass ratio. Before measuring the mass of the crucible and sample after the 3rd heating, the crucible was broken. Also, the change in mass between the second and third heating was 0.009 g, which is greater than the 0.007 g change in mass between the first and second heating. Theoretically the change in mass should decrease with each subsequent heating, as there is less and less water available to be evaporated from the sample. It is possible that some mass was lost when the crucible broke, either from the sample or from the crucible. This would falsely indicate higher water content. In addition, the mass reported by the scale would fluctuate by a factor of nearly ±0.010 g during the measurements, so human error was introduced in an attempt to estimate the mass at a 0.001 g level of precision. The combination of these factors may have been enough to cause the 1.84% difference in the water mass ratio of goslarite and the unknown sample.Part IIThe objective of Part II was to observe precipitation and acid/base reactions, as well as distinguish between dissolution and dissociation.DISCUSSION QUESTIONS1. Four astronauts would need 28 kg, or 1554.3 moles of water in one week. Because epsomite has a 1:7 ratio with water, this means that 222.1 moles of epsomite would, once dehydrated, provide enough water. With a molecular weight of 138.376 g/mol, the astronauts would have to dehydrate 30.73 kg of epsomite to obtain 28 kg of water.2. In most acid/base reactions, a change in pH indicates that a reaction took place. Other indicators include gas formation, salt formation, and heat production. In this lab, the primary indication was a change in pH, although the HCL (aq) + NaHCO3 (s) reaction produced a