Can someone help me with these questions please?
I have a 50ml cylinder filled with 7.0562g of NaHCO3 and water.
What is the volume of the solution in L?
What is the moles of NaHCO3?
What is the molarity of the NaHCO3 solution in units of mol/L?
If the density of the solution is 1.047 g/mL, what is the molarity of the solution in units of mol/kg?
What is the mass percent of sodium bicarbonate in the solution?
what is the mole fraction of sodium bicarbonate in the solution?
I have a 50ml cylinder filled with 7.0562g of NaHCO3 and water.
What is the volume of the solution in L?
What is the moles of NaHCO3?
What is the molarity of the NaHCO3 solution in units of mol/L?
If the density of the solution is 1.047 g/mL, what is the molarity of the solution in units of mol/kg?
What is the mass percent of sodium bicarbonate in the solution?
what is the mole fraction of sodium bicarbonate in the solution?
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OK, lets start at the beginning.
You have a 50ml cylinder containing 50ml, right, water and NaHCO3? (That's sodium bicarbonate, by the way)
1. V of solution in L.
1 L = 1000ml
Conversion: 50ml (1L/1000ml), ml cancels, you're left with liters. 50/1000 = 0.05 L
2. Find mol NaHCO3.
Conversion: molar mass (what you have)
First, find the molar mass NaHCO3. http://www.ptable.com
N=23 H=1 C=12 O=16(x3) = 23+1+12+48 = 84g/mol
You put 7.0562g in solution. 7.0562g (1mol/84g) = 0.0840mol NaHCO3 in solution.
3. Find M, molarity of solution.
M = mols/Liters automatically, so "finding M in units of mol/L" is a trick question.
M= 0.0840mol/0.05L = 1.68M (mol/L)
4. Don't know this one... There's a way to convert SOLUTIONS to mol/kg, since water is 1L/1Kg, but I'm not sure what it is.
5. Find Mass % of NaHCO3 in solution.
http://chemistry.about.com/od/workedchem…
First you find the elemental mass FOR EACH ELEMENT, and divide Each by the molar mass (both in grams). Then multiply that answer by 100 to get percent. If they don't add up to 100 (or nearly with rounding), you made an error somewhere.
** got lucky -- when I looked it up to refamiliarize myself with "mass percent", the example was for NaHCO3!**
6. Mole Fraction
https://chemistry.twu.edu/tutorial/MolFr…
Trick question... mole fraction in solution is MOLARITY.
You have a 50ml cylinder containing 50ml, right, water and NaHCO3? (That's sodium bicarbonate, by the way)
1. V of solution in L.
1 L = 1000ml
Conversion: 50ml (1L/1000ml), ml cancels, you're left with liters. 50/1000 = 0.05 L
2. Find mol NaHCO3.
Conversion: molar mass (what you have)
First, find the molar mass NaHCO3. http://www.ptable.com
N=23 H=1 C=12 O=16(x3) = 23+1+12+48 = 84g/mol
You put 7.0562g in solution. 7.0562g (1mol/84g) = 0.0840mol NaHCO3 in solution.
3. Find M, molarity of solution.
M = mols/Liters automatically, so "finding M in units of mol/L" is a trick question.
M= 0.0840mol/0.05L = 1.68M (mol/L)
4. Don't know this one... There's a way to convert SOLUTIONS to mol/kg, since water is 1L/1Kg, but I'm not sure what it is.
5. Find Mass % of NaHCO3 in solution.
http://chemistry.about.com/od/workedchem…
First you find the elemental mass FOR EACH ELEMENT, and divide Each by the molar mass (both in grams). Then multiply that answer by 100 to get percent. If they don't add up to 100 (or nearly with rounding), you made an error somewhere.
** got lucky -- when I looked it up to refamiliarize myself with "mass percent", the example was for NaHCO3!**
6. Mole Fraction
https://chemistry.twu.edu/tutorial/MolFr…
Trick question... mole fraction in solution is MOLARITY.
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