The answer is A, biogeochemical cycles.
Formula units in 450 g of
is 1.93 × 10²⁴ formula units.
<u>Explanation:</u>
First we have to find the number of moles in the given mass by dividing the mass by its molar mass as,
![$\frac{450 g}{142.04 g/mol} = 3.2 moles](https://tex.z-dn.net/?f=%24%5Cfrac%7B450%20g%7D%7B142.04%20g%2Fmol%7D%20%3D%20%203.2%20moles)
Now, we have to multiply the number of moles of Na₂SO₄ by the Avogadro's number, 6.022 × 10²³ formula units/mol, so we will get the number of formula units present in the given mass of the compound.
3.2 mol × 6.022 × 10²³ = 1.93 × 10²⁴ formula units.
So, 1.93 × 10²⁴ formula units is present in 450g of Na₂SO₄.
Period are going left to right across the periodic table
Groups are going up to down on the periodic table
Answer:
![Y=85\%](https://tex.z-dn.net/?f=Y%3D85%5C%25)
Explanation:
Hello!
In this case, since we know the balanced chemical reaction, we are first able to realize there is a 1:3 mole ratio between zinc phosphate and zinc chloride; it means that we can first compute the moles of the desired product via stoichiometry:
![n_{ZnCl_2}=20gZn_3(PO_4)_2*\frac{1molZn_3(PO_4)_2}{386.11gZn_3(PO_4)_2}*\frac{3molZnCl_2}{1molZn_3(PO_4)_2}=0.16gZnCl_2](https://tex.z-dn.net/?f=n_%7BZnCl_2%7D%3D20gZn_3%28PO_4%29_2%2A%5Cfrac%7B1molZn_3%28PO_4%29_2%7D%7B386.11gZn_3%28PO_4%29_2%7D%2A%5Cfrac%7B3molZnCl_2%7D%7B1molZn_3%28PO_4%29_2%7D%3D0.16gZnCl_2)
Next, since those moles are associated with the theoretical yield of zinc chloride, we obtain the corresponding mass:
![m_{ZnCl_2}^{theoretical}=0.16molZnCl_2*\frac{136.29gZnCl_2}{1molZnCl_2} =21gZnCl_2](https://tex.z-dn.net/?f=m_%7BZnCl_2%7D%5E%7Btheoretical%7D%3D0.16molZnCl_2%2A%5Cfrac%7B136.29gZnCl_2%7D%7B1molZnCl_2%7D%20%3D21gZnCl_2)
Finally, we compute the percent yield by diving the actual yield (18 g) by the theoretical yield:
![Y=\frac{18g}{21g}*100\%\\\\Y=85\%](https://tex.z-dn.net/?f=Y%3D%5Cfrac%7B18g%7D%7B21g%7D%2A100%5C%25%5C%5C%5C%5CY%3D85%5C%25)
Best regards!
Absorbance is related to the concentration of a substance using the Beer-Lambert's Law. According to this law, absorbance is linearly related to concentration. However, this is only true up to a certain concentration depending on the substance. For this case, we assume that the said law is applicable.
A = kC
Using the first conditions, ewe solve for k.
0.26 = k (0.10)
k = 2.6
A = kC
A = 2.6 (0.20) = 0.52
Therefore, the absorbance at a concentration of 0.20 M and wavelength of 500nm is 0.52.