What mass of MgCO3 is contained in a 2.750g solid sample consisting of only MgCO3 and MgO if heating to decompose all the MgCO3 according to the following equation leaves a solid residue weighing 2.160g? Magnesium oxide is unaffected by the heat. MgCO3(s) MgO (s) + Co2 (g) 2. a) Consider the reaction of question 2. Suppose a 3.250 g sample containing only MgCO3 and MgO is 42.6% MgO. How many grams of CO2 would be liberated by complete thermal decomposition of the MgCO3 in the sample?
Find the volume of 2.40 mol of gas whose temperature is 50.0 °C and whose pressure is 202 kPa. 6. How many moles of gas are contained in a 50.0 L cylinder at a pressure of 10100 kPa and a temperature of 35.0 °C? 7. Determine the number of grams of carbon dioxide in a 450.6 mL tank at 1.80 atm and minus 50.5 °C.
(Divide the mass of the solid by the volume calculated above.) Trial 1: 27 / 39.75 = .679 Trial 2: 27 / 60 = .45 Trial 3: 25.5 / 31.5 = .81 Questions and Conclusions: How would you determine the proper number of significant figures of a liquid using a graduated cylinder?
Lab 4: Determination of Percent by Mass of the Composition in a Mixture by Gravimetric Analysis Introduction Thermal gravimetric analysis is used to determine the percent by mass is used to determine the percent by mass of a component in a mixture. When a mixture is heated to an appropriately high temperature, one component in the mixture decomposes to form a gaseous compound. The mass of this particular component is related to the mass of the gaseous compound. In this experiment, the percent by mass of sodium hydrogen carbonate (NaHCO3) and potassium chloride (KCl) in a mixture will be determined. Experimental First, we weighed 2 samples, each has 1 gram of NaHCO3-KCl mixture Second, we put the samples in 2 crucibles (A and B) and weighed them.
The two unknown solids are weighed to a mass of 0.15g each. The unknown solids are dropped carefully into the corresponding Erlenmeyer flask wit 50mL of distilled water. The solid in the water must be dissolved and afterwards add 10 drops of Bromecresol green to indicate the change of color when the solution has been titrated. The flask should start with a blue tint. HCl is carefully dropped into the Erlenmeyer flasks with the primed pipette until the solution turn to a green tint.
* Trial 1 36-25.5=10g * Trial 2 36-25=11g * Trial 3 35.5-25=10g 2. Calculate the density of the unknown liquid for each trial. (Divide the mass of the liquid calculated above by the volume of the liquid.) * Trial 1: 10.5/50=0.20g/mL * Trial 2: 11/49=0.20 g/mL
A small bottle of lead shot was also used to experimentally estimate the value of the packing coefficient. A 10 mL graduated cylinder was taken, filled with lead shot to about 10.0 mL and the total empty space volume between the lead balls was found. For the measurement of molecular size in liquids and solids, a clean 50 mL graduated cylinder was weighed and had 20 mL of distilled water added to it. The mass difference between the exact volume of water and the exact mass of the graduated cylinder was used to calculate the water density and the molecular size of the water molecules. For the measurement of molecular size in solids and gases, a measured solid dry ice sample was placed in a 125 mL glass flask, and a rubber balloon was placed over the neck of the flask.
Contents Page Experiment 1 Calibration of a 25-mL Pipette 1 Experiment 2 Volumetric Analysis 3 Experiment 3 Experiment 4 Experiment 5 Gravimetric Determination of Nickel Sodium Acid Salt of Heptaoxodiphosphoric Acid Synthesis and Stoichiometric Analysis of Hexaamminenickel(II) Chloride 5 6 9 Experiment 1: Calibration of a 25-mL Pipette Background The graduation mark on a pipette being usually made at 20°C (whereas room temperature is much higher than this), the volume of the pipette must be calibrated before any volumetric analysis is carried out. Otherwise, the error in the graduation mark may exceed the error allowed in a measurement. A pipette is designed to deliver only one fixed volume of a liquid and it is calibrated for this volume only. Accuracy to two decimal places in mL is generally possible. The pipette is calibrated by weighing distilled water in it at room temperature, and then calculating the volume from the weight of water in air.
The cylinder was weighed empty, and then graduated cylinder was filled to a certain volume according to the graduations on it and weighed again. The difference in weight was divided by the volume gives the weight per unit volume of the fluid. The liquid density was calculated. The mass per unit volume, or the density, was thus measured in a direct way.  Part II – Viscosity The diameter and weight of five of the test spheres were measured and then the volume and density of each sphere were computed.
When the volume is halved from 20.0 mL to 10.0 mL the pressure is almost doubled from 53.22 kPa to 104.54 kPa. The relationship between the pressure and volume of a confined gas is inverse. The line of the graph is curved not straight. This indicates an indirect relationship. The amount of the gas and the temperature are assumed to be constant in this experiment.