04-11-2018, 02:54 PM

Hello my scientific community, I have just begun my Chem 101 classes at college. I became overly frustrated with a few problems and have turned to the internet for some answers. Hopefully this method of education will help solidify my understanding. Most of the trouble that I am having is with conversion, for example, when and how to convert the units of measurements. Another issue I am having is when given the problem, how would I know which unit to use as the numerator and which as the denominator. Lastly, when there are multiple measurements within the same unit, for example, 10 g cm3/s2, how to convert and reduce it. If possible, explaining it in grandma terms, I'm sure would work best. Here we go:

1) The roof of a building is 0.2 km2. During a rainstorm, 5.5 cm of rain was measured to be sitting on the roof. What is the mass of the water on the roof after the rainstorm?

For this question, I had it explained to me, but I am still not fully understanding it. I am not sure how density is factored into it, how is it related to mass.

2) Convert 10 g cm3/s2 to kg m3/h2?

3) The bromine content of the ocean is ≈65 g of bromine per million g of sea water. How many cubic meters of ocean must be processed to recover 500 mg of bromine, if the density of sea water is 1.0x103 kg/m3?

4) If 20 g of coal are burned heating 1 L of water, how much hotter will the water get? Assume all of the heat lost by the coal is gained by the water. Additional information: density of water: 1 g/mL, specific heat of water: 4.18 J/((g)(C°)), density of coal: 1506 kg/m3, heat of combustion of coal: 27 MJ/kg.

5) How many phosphite ions are in one molecular (I'm not sure if this is a typo or not? Possibly mole?) of magnesium phosphite?

6) How many moles of ions are formed when 21.3 g of aluminum nitrate are dissolved in water (the solid dissolves and ionizes completely)?

7) Consider the mass spectrum of propane C3H8. At what value of m/z is the molecular ion peak for propane located?

Any help would be much appreciated, I understand that it is a lot of work and information.

Thank you!

1) The roof of a building is 0.2 km2. During a rainstorm, 5.5 cm of rain was measured to be sitting on the roof. What is the mass of the water on the roof after the rainstorm?

For this question, I had it explained to me, but I am still not fully understanding it. I am not sure how density is factored into it, how is it related to mass.

2) Convert 10 g cm3/s2 to kg m3/h2?

3) The bromine content of the ocean is ≈65 g of bromine per million g of sea water. How many cubic meters of ocean must be processed to recover 500 mg of bromine, if the density of sea water is 1.0x103 kg/m3?

4) If 20 g of coal are burned heating 1 L of water, how much hotter will the water get? Assume all of the heat lost by the coal is gained by the water. Additional information: density of water: 1 g/mL, specific heat of water: 4.18 J/((g)(C°)), density of coal: 1506 kg/m3, heat of combustion of coal: 27 MJ/kg.

5) How many phosphite ions are in one molecular (I'm not sure if this is a typo or not? Possibly mole?) of magnesium phosphite?

6) How many moles of ions are formed when 21.3 g of aluminum nitrate are dissolved in water (the solid dissolves and ionizes completely)?

7) Consider the mass spectrum of propane C3H8. At what value of m/z is the molecular ion peak for propane located?

Any help would be much appreciated, I understand that it is a lot of work and information.

Thank you!