General Chemistry Questions (Solubility)

In summary, the conversation discusses solving for the masses of propane and butane in a gaseous fuel mixture and finding the molarities of each ion in a solution containing Na2CO3, Ca(NO3)2, and AgNO3. It also mentions determining which salt has the higher Ksp in order to determine which will precipitate first.
  • #1
dekoi
Please help me with the following problems.

1.)(85) A 55-g sample of a geseous fuel mixture contains 0.51 fraction propane C3H8; the remainder is butane. What are masses of propane and butane in sample?

Using the formula: Ax = n(solute)/n(total), i initially solved for total moles. I went about this by multiplying 7 by the molar mass of carbon (there is a total of 7 carbons) and similarly, 18 by the molar mass of hydrogen. This allows me to solve for moles of solute, which i then convert into mass. However, i get an answer of 12.1g and 43.0 g, which differs from the book.

2.) (105) A solution has 0.375 mol Na2CO3, 0.125 mol Ca(NO3)2, and 0.200 mol AgNO3 in 2.0 L of water. Write balanced reactions and calculate molarities of each ion.

I noticed that NO3(-1) is always soluble. CO3(2-) can form solids with Ca+ and Ag+. So i wrote two separate reactions, one in which CaCO3 was the solid, and the other in which Ag2CO3 was the solid. This allowed me to get the moles of Na+, which i then converted into molarity. But I'm not sure this is the correct way of approaching this question.


Thank you.
 
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  • #2
Anyone ?




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  • #3
Using the formula: Ax = n(solute)/n(total), i initially solved for total moles. I went about this by multiplying 7 by the molar mass of carbon (there is a total of 7 carbons) and similarly, 18 by the molar mass of hydrogen. This allows me to solve for moles of solute, which i then convert into mass. However, i get an answer of 12.1g and 43.0 g, which differs from the book.

I'm not quite sure what you're going for here. When they refer to fraction, are they referring to mole fraction or mass fraction?

2.) (105) A solution has 0.375 mol Na2CO3, 0.125 mol Ca(NO3)2, and 0.200 mol AgNO3 in 2.0 L of water. Write balanced reactions and calculate molarities of each ion.

it'll depend on which has the higher Ksp, the less soluble salt will precipitate almost exclusively, but in this case you have enough carbonate ions to precipitate both Ag and Ca, you'll just need to determine, the amount of carbonate left over, if any, remembering that 2 Ag+ is required for every carbonate...all of this assuming that both of the precipitates involving silver and calcium are completely insoluble (which is what your teacher probably wants).


the molarity of Na+ is simply 2 x .375/2.0L.

assuming that all of Ag and Ca precipitate, which you'll need to figure out, all that's left is to find the moles of carbonate remaining in solution. Of course you'll need to add up all of the moles of nitrate and divide by volume to find its molarity.
 

Related to General Chemistry Questions (Solubility)

1. What is solubility?

Solubility is a measure of how much of a substance (known as the solute) can dissolve in a specific amount of another substance (known as the solvent) to form a homogeneous mixture. It is typically expressed in grams of solute per 100 milliliters of solvent.

2. What factors affect solubility?

The solubility of a substance can be affected by several factors, including temperature, pressure, and the chemical nature of the solute and solvent. Generally, increasing the temperature and pressure can increase the solubility of solids and gases, respectively. The chemical nature of the solute and solvent can also play a role in determining solubility, as some substances are more polar or nonpolar than others, which can affect their ability to dissolve in certain solvents.

3. How is solubility measured?

Solubility is typically measured experimentally by adding a known amount of solute to a fixed amount of solvent and observing whether the solute completely dissolves or not. The resulting concentration of the solute in the solvent can then be calculated to determine its solubility.

4. What is the difference between a saturated and unsaturated solution?

A saturated solution is one in which the solvent has dissolved the maximum amount of solute possible at a given temperature and pressure. Any additional solute added to a saturated solution will not dissolve and will instead form a precipitate. An unsaturated solution, on the other hand, is one in which the solvent has not reached its maximum capacity to dissolve the solute, and more solute can still be dissolved.

5. How can solubility be used in everyday life?

Solubility plays a role in many everyday activities, such as cooking, cleaning, and even taking medication. For example, the solubility of salt in water is essential for seasoning food while cooking. In cleaning, certain substances are chosen for their solubility in water, making them effective at dissolving dirt and grime. And in medicine, solubility affects how quickly and effectively a drug can be absorbed by the body.

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