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Eddi Din [679]
4 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]4 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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When 9.36 g sodium hydroxide is dissolved in enough water to make a total volume of 965 mL, what is the concentration of the res
SSSSS [86.1K]

Answer:

0.2425 M

Explanation:

Given mass = 9.36 g

Molar mass of NaOH = 39.997 g/mol

The formula for the calculation of moles is shown below:

moles = \frac{Mass\ taken}{Molar\ mass}

Thus,

Moles= \frac{9.36\ g}{39.997\ g/mol}

Moles\ of\ NaOH= 0.234\ mol

Given that:- Volume = 965 mL = 0.965 L ( 1 mL = 0.001 L )

So,

Considering:

Molarity=\frac{Moles\ of\ solute}{Volume\ of\ the\ solution}

Molarity=\frac{0.234\ mol}{0.965\ L}=0.2425\ M

5 0
4 years ago
Read 2 more answers
Rank the following substances in order from most soluble in water to least soluble in water: methane, CH4; 2-butanol, C4H9OH; ma
inna [77]

Answer:

MgCl2 > C4H9OH > CH4 > C3H8.

Explanation:

Alkanes do not form hydrogen bonds and are insoluble in polar solvents e.g water. The hydrogen bonds between water molecules are move away from an alkane molecule and this worsens as their Carbon chain / molecular weight increases.

MgCl2 is soluble in water. Water essentially breaks down the ionic crystal lattice and the resulting solution is slightly basic.

Alcohols are generally soluble in water and this is because of the -OH group and its ability to form hydrogen bonds with water molecules. As applied to alkanes, as the carbon chain in the alkyl group increases, the solubility decreases.

From the most soluble to the least soluble,

MgCl2 > C4H9OH > CH4 > C3H8.

4 0
3 years ago
Which of the following statements about metalloids is true?
Klio2033 [76]
Metalloids had properties that fall between those of metals and nonmetals (I believe that to be correct-.-)
7 0
3 years ago
Read 2 more answers
Acetic acid (HC2H3O2) is the active ingredient in vinegar. Calculate the mass percent composition of O in acetic acid.
skelet666 [1.2K]

Answer:

53.29% of acetic acid is Oxygen

Explanation:

Step 1: Given data

Acetic acid it's molecular formula is HC2H3O2. This means it consists of 3 elements Carbon, Hydrogen and oxygen.

Step 2: the molar masses

The molecular mass of acetic acid is:

4* H = 4* 1.01 g/mole

2* C = 2*12 g/mole

2*O = 2* 16 g/mole

Total molar mass = 4+ 24+32 = 60.052 g/mole

Step 3: Calculate the mass percent

32 g of the 60.052 g is Oxygen

(32/60.052) *100% = 53.29%

53.29% of acetic acid is Oxygen.

7 0
3 years ago
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¿ ppr que no podemos automedicarnos ,cuando pensamos q tenemos el virus del CIVD-19?
GREYUIT [131]

Answer:

Porque como tu no eres profesional en medicina, no sabes nada sobre las dosis de medicamentos ni de los efectos que pueden tener en tu cuerpo si se administran incorrectamente.

Explanation:

Es logico que solo vayas al medico para que te den la cura allí.

3 0
3 years ago
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