CHM 1045L (002)
theoretical percentage of Mg in MgO
(periodic table) Mg- 24.305+ O-15.999= 40.304 24.305 divided 40.304= 60.304%
How many mm in a cm?
10 mm
Explain how you will find the mass of oxygen gas produced in this experiment.
It will take the mass of potassium chlorate before the reaction and subtract is from the mass of the potassium chlorate after the reaction, this will tell me in grams how much oxygen gas was produced.
After adding DI water to your crucible, you do not burn the sample until dryness. How does this error affect you calculated % Mg?
It's going to add to the mass of the MgO. The added water can affect the percentage of Mg; it will be smaller than it should be.
How does not properly using a bunsen burner and inefficiently burning your Mg affect the calculated % Mg ?
Not enough MgO will be too small, and the reaction could not get a full completion. Then when you calculate the percentage of Mg it will be too large. If the Bunsen burner is not hot enough the Mg will not react correctly.
Suppose at the end of your experiment, you spill some of your white powder before weighing. How does this affect your calculated % Mg?
The Mg percentage would be too large and the mass of the MgO would be too small. This will affect the percentage of the Mg outcome and make it too large.
Based on the deviation between your predicted concentrations and the concentrations obtained from the calibration curve, what conclusions can you make about what tools should be used to make solutions in the lab? explain why you think the tools used in part B were not adequate for making solutions.
Using a graduated cylinder is the best tool to get better results. The flasks and beakers were not the best tools to get good results. The tools in part B were not adequate enough for making the solutions because the absorbances were way off from the concentrations.
What is a calibration curve?
a plot of concentration versus absorbance which shows a positive linear relationship between the two properties
What does the Law of Conservation of Mass state? How does this relate to chemical reactions?
all mass that the reaction has, in the beginning, is kept with the original product in a chemical reaction. This relates to chemical reactions because all the contents that are together will contact each other to form a new reaction.
What does the Law of Constant Composition state? How does this relate to the thermal decomposition of potassium chlorate?
every sample of potassium chlorate, regardless of size, will be made up of potassium, chlorine, and oxygen in a 1:1:3 ratio. This relates to the thermal decomposition of potassium chlorate because once potassium chlorate is heated, it decomposes and turns into a solid. Once it is a solid, it will still be made up of potassium, chlorine, and oxygen; it is just all mixed to create a chemical reaction.
distance is measured with
kilometers
Meniscus
lowest curved point in a liquid
What is the % of KClO3 that must have been in the unknown mixture?
mass of KClO3 mixture divided by mass of unknown times 100
Percent of Mg in the MgO
mass of Mg divided by MgO times 100
Moles of O2 produced?
mass of O2 produced divided by oxygen 32.00
Mass of Mg in Sample
mass of crucible, lid, Mg metal - mass of crucible and lid
Mass of O in sample
mass of crucible, lid, MgO - mass of crucible, lid, Mg metal
Mass of MgO
mass of crucible, lid, MgO -mass of crucible and lid
a classroom is measured in
meters
Mass of KClO3 that must have been in the unknown mixture?
moles of KCLO3 times mass of potassium chlorate.
What is the moles of KClO3 that must have been the unknown mixture?
moles of O2 produced time 2/3 (3 sig figs)
percent error
percent of MgO - theoretical divided by theoretical time 100
mass
the amount of matter in an object
Molarity
the mole solute divided by the liters solution. Number of moles of the dissolving substance in one liter of solution
Mass of O2 has produced?
unknow-after
What is the mass of the unknown mixture?
unknown-catalyst