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Eddi Din [679]
3 years ago
15

What would you need to know in order to calculate how many pre-1982 pennies and post-1982 pennies are in the mixed sample?

Chemistry
1 answer:
ololo11 [35]3 years ago
8 0
<span>In 1982, the physical composition of the penny was changed; the ratio of the zinc to copper was essentially reversed. As a result, a pre-82 penny has a different density from a post-82 penny. It would help to know several things: first, the average mass and density of both a single pre and post 82 penny. Then you need to know how many pennies in total are in the mixed sample. You would also need to know the mass and density measures of "pure" samples, that is, if we have a mixed sample of 20 pennies, it would be useful to know the mass and density measurements of 20 pre-82 and 20 post-82 pennies. You can then figure out your estimate based on the variances in the density measurements.</span>
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I have a mass of 30 grams and a volume of 60 cm3 what is the density
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2 years ago
0.2640 g of sodium oxalate is dissolved in a flask and requires 30.74 mL of potassium
Free_Kalibri [48]

Moles of potassium permanganate = 0.0008

<h3>Further explanation  </h3>

Titration is a procedure for determining the concentration of a solution by reacting with another solution which is known to be concentrated (usually a standard solution). Determination of the endpoint/equivalence point of the reaction can use indicators according to the appropriate pH range  

Reaction

5Na2C2O4(aq) + 2KMnO4(aq) + 8H2SO4(aq) ---> 2MnSO4(aq) + K2SO4(aq) + 5Na2SO4(aq) +  10CO2(g) + 8H2O(1)

The end point ⇒titrant and analyte moles equal

titrant : potassium  permanganate-KMnO4

analyte : sodium oxalate - Na2C2O4

so moles of KMnO4 = moles of Na2C2O4

moles of Na2C2O4(mass = 0.2640 g, MW=134 g/mol) :

\tt mol=\dfrac{mass}{MW}\\\\mol=\dfrac{0.264}{134 g/mol}\\\\mol=0.002

From equation, mol ratio  Na2C2O4 : KMnO4 = 5 : 2, so mol KMnO4 :

\tt \dfrac{2}{5}\times 0.002=0.0008

6 0
3 years ago
A dialysis unit requires 70000 mL of distilled water. How many gallons of water are needed? (1 gal = 4 qt)
Lady bird [3.3K]

Answer: 19.25 gallons

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Given:  4 quarts = 1 gallon

Thus if 1 ml is equal to 0.0011 quart

70000 ml  is equal to =\frac{0.0011}{1}\times 70000=77quart

Now if 4 quarts is equal to 1 gallon.

77 quarts is is equal to=\frac{1}{4}\times 77=19.25gallons




5 0
3 years ago
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Which of the following describes a characteristic of water that makes it cohesive in nature?
kari74 [83]

Answer:

D is answer

Explanation:

8 0
3 years ago
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