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Salsk061 [2.6K]
3 years ago
13

In 1993 the Minnesota Department of Health set a health risk limit for chloroform in groundwater of 60.0 g/L Suppose an analytic

al chemist receives a sample of groundwater with a measured volume of 79.0 mL. Calculate the maximum mass in milligrams of chloroform which the chemist could measure in this sample and still certify that the groundwater from which it came met Minnesota Department of Health standards. Be sure your answer has the correct number of significant digits. mg
Chemistry
1 answer:
tangare [24]3 years ago
6 0

Answer:

4.74 × 10³ mg

Explanation:

Given data

  • Health risk limit for chloroform in groundwater: 60.0 g/L
  • Volume of the sample of groundwater: 79.0 mL = 79.0 × 10⁻³ L

The maximum mass of chloroform that there could be in the sample of groundwater to meet the standards are:

79.0 × 10⁻³ L × 60.0 g/L = 4.74 g

1 gram is equal to 10³ milligrams. Then,

4.74 g × (10³ mg/1 g) = 4.74 × 10³ mg

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Hydrogen gas (a potential future fuel) can be formed by the reaction of methane with water according to the following equation:
rusak2 [61]

Answer:

60.42% is the percent yield of the reaction.

Explanation:

Moles of methane gas at 734 Torr and a temperature of 25 °C.

Volume of methane gas = V = 26.0 L

Pressure of the methane gas = P = 734 Torr = 0.9542 atm

Temperature of the methane gas = T = 25 °C = 298.15 K

Moles of methane gas = n

PV=nRT

n=\frac{PV}{RT}=\frac{0.9542 atm\times 26.0L}{0.0821 atm L/mol K\times 298.15 K}=1.0135 mol

Moles of water vapors at 700 Torr and a temperature of 125 °C.

Volume of water vapor = V' = 23.0 L

Pressure of water vapor = P' = 700 Torr = 0.9100 atm

Temperature of  water vapor = T' = 125 °C = 398.15 K

Moles of water vapor gas = n'

P'V'=n'RT'

n'=\frac{PV}{RT}=\frac{0.9100 atm\times 23.0L}{0.0821 atm L/mol K\times 398.15 K}=0.6402 mol

CH_4(g)+H_2O(g)\rightarrow CO(g)+3H_2(g)

According to reaction , 1 mol of methane reacts with 1 mol of water vapor. As we can see that moles of water vapors are in lessor amount which means it is a limiting reagent and formation of hydrogen gas will depend upon moles of water vapors.

According to reaction 1 mol of water vapor gives 3 moles of hydrogen gas.

Then 0.6402 moles of water vapor will give:

\frac{3}{1}\times 0.6402 mol=1.9208 mol of hydrogen gas

Moles of hydrogen gas obtained theoretically = 1.9208 mol

The reaction produces 26.0 L of hydrogen gas measured at STP.

At STP, 1 mole of gas occupies 22.4 L of volume.

Then 26 L of volume of gas will be occupied by:

\frac{1}{22.4 L}\times 26 L= 1.1607 mol

Moles of hydrogen gas obtained experimentally = 1.1607 mol

Percentage yield of hydrogen gas of the reaction:

\frac{Experimental}{Theoretical}\times 100

\%=\frac{ 1.1607 mol}{1.9208 mol}\times 100=60.42\%

60.42% is the percent yield of the reaction.

8 0
3 years ago
Suppose it took 108 joules of energy to raise a bar of gold from 25 °C to 29.7°C. Given that the specific heat capacity of gold
Lady bird [3.3K]

Answer:

m = 180 g

Explanation:

Given data:

Energy absorbed = 108 J

Mas of gold = ?

Initial temperature = 25°C

Final temperature = 29.7 °C

Specific heat capacity of gold = 0.128 J/g.°C

Solution:

Formula:

Q = m.c. ΔT

Q = amount of heat absorbed or released

m = mass of given substance

c = specific heat capacity of substance

ΔT = change in temperature

ΔT =29.7 °C - 25°C

ΔT = 4.7 °C

108 J = m ×0.128 J/g.°C ×4.7 °C

108 J = m ×0.60 J/g

m = 108 J/0.60 J/g

m = 180 g

3 0
3 years ago
Why are the electrons in a nitrogen-phosphorus covalent bond not shared equally? which atom do the electrons spend more time aro
a_sh-v [17]
<span>Electrons in a nitrogen-phosphorus covalent bond are not shared equally because nitrogen and phosphorus do not have the same electronegativity. The atoms spend more time around the most electronegative atom nitrogen.</span>
6 0
4 years ago
Why is frying an egg an example of a chemical change
skelet666 [1.2K]
A Chemical change is any form of chemical reaction changing the state of the matter involved. When you fry an egg, you are making a reaction between the heat and the chemicals that make up the egg. Therefore once you have fried that egg, you have completed a chemical reaction. This is why it's a chemical change when you fry an egg.
8 0
3 years ago
Read 2 more answers
What are families 3-12 on the periodic table called
fredd [130]

Answer:

transition elements

Explanation:

6 0
3 years ago
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