Answer:
The concentration the student should write down in her lab is 2.2 mol/L
Explanation:
Atomic mass of the elements are:
Na: 22.989 u
S: 32.065 u
O: 15.999 u
Molar mass of sodium thiosulfate, Na2S2O3 = (2*22.989 + 2*32.065 + 3*15.999) g/mol = 158.105 g/mol.
Mass of Na2S2O3 taken = (19.440 - 2.2) g = 17.240 g.
For mole(s) of Na2S2O3 = (mass taken)/(molar mass)
= (17.240 g)/(158.105 g/mol) = 0.1090 mole.
Volume of the solution = 50.29 mL = (50.29 mL)*(1 L)/(1000 mL)
= 0.05029 L.
To find the molar concentration of the sodium thiosulfate solution prepared we use the formula:
= (moles of sodium thiosulfate)/(volume of solution in L)
= (0.1090 mole)/(0.05029 L)
= 2.1674 mol/L
Mass number of an element write in bottom of it!
So, there 80 would be the mass number of ₈₀Br.
Hope this helps!
Oh we have just done this in biology recently... photolysis occurs where it splits apart water molecules to make electrons and hydrogen ions (the H+ is used to reduce NaDP later on) and also O₂ is made as a by product
basically this is the equation 2H₂O⇒4e⁻ + 4H⁺ where the electrons replace the lost ones in chlorophyll
hope this helped :)
Option A is right answer that is Na is smaller than K.
Answer:
32.3%
Explanation:
Percent yield is defined as:
Actual yield (125.5g) / Theoretical Yield * 100
To find theoretical yield we have to find the moles of aluminium. As 2 moles of Al produce 2 moles of AlCl3, the moles of Al = Moles AlCl3.
With these moles we can find the mass assuming a 100% of yield (Theoretical Yield) as follows:
<em>Moles Al = Moles AlCl3 (Molar mass Al = 26.98g/mol)</em>
72g Al * (1mol / 26.98g) = 2.67 moles AlCl3
<em>Mass AlCl3 (Molar mass: 133.34g/mol)</em>
2.67 moles AlCl3 * (133.34g / mol) = 355.8g AlCl3
Percent Yield = 125.5g / 355.8g * 100 =
<h3>32.3% </h3>
