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Anastasy [175]
2 years ago
15

Lead is a toxic metal that affects the central nervous system. A Pb-contaminated water sample contains 0.0011% Pb by mass. How m

uch of the water (in mL) contains 150 mg of Pb
Chemistry
1 answer:
Shalnov [3]2 years ago
6 0

Lead is a toxic metal that affects the central nervous system. A Pb-contaminated water sample contains 0.0011% Pb by mass. 13.6 × 10³ ml water contains 150 mg of Pb.

<h3>How to calculate the mass of solution ? </h3>

Given percentage of Pb present in the sample solution is 0.0011%

That means 0.0011 grams of Pb present in the 100g of solution.

So,

= \frac{0.150\ \text{g Pb} \times 100\ \text{g water}}{0.0011\ \text{g of Pb}}

= 13.6 × 10³ g water

<h3>What is Density ? </h3>

The mass per unit volume is called density. Density is represented as D or ρ.

It is expressed as:

\rho = \frac{m}{V}

where,

ρ = Density

m = mass of the object

V = Volume of object

Now put the value in above expression we get

\rho = \frac{m}{V}

1\ g/ml = \frac{13.6 \times 10^3}{V}

V = 13.6 × 10³ ml

Thus from the above conclusion we can say that Lead is a toxic metal that affects the central nervous system. A Pb-contaminated water sample contains 0.0011% Pb by mass. 13.6 × 10³ ml water contains 150 mg of Pb.

Learn more about the Density here: brainly.com/question/1354972

#SPJ4

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The temperature of evaporation is much higher for water than for alcohol. Without knowing more about the chemistry of alcohol, w
Valentin [98]

Answer:

Fewer hydrogen bonds form between alcohol molecules. As a result, less heat is needed for alcohol molecules to break away from solution and enter the air.

Explanation:

Hydrogen bonding is a kind of intermolecular interaction that occurs when hydrogen is bonded to a highly electronegative atom.

Both water and alcohols exhibit hydrogen bonding. However, alcohols exhibit fewer hydrogen bonds than water.

As a result of this, the temperature of evaporation is much higher for water than for alcohol because hydrogen bonds hold water molecules more closely than alcohol molecules are held.

8 0
3 years ago
Half of the first 18 elements have an odd number of electrons, and half have an even number. Show why atoms of these elements ar
asambeis [7]

Answer:

Diamagnetism in atom occurs whenever two electrons in an orbital paired equalises with a total spin of 0.

Paramagnetism in atom occurs whenever at least one orbital of an atom has a net spin of electron. That is a paramagnetic electron is just an unpaired electron in the atom.

Here is a twist even if an atom have ten diamagnetic electrons, the presence of at least one paramagnetic electron, makes it to be considered as a paramagnetic atom.

Simply put paramagnetic elements are one that have unpaired electrons, whereas diamagnetic elements do have paired electron.

The atomic orbital and radius increases by gaining electron linearly so even electron numbered atoms are diamagnetic while the odd electron numbered atoms are paramagnetic.

Running through the first 18 elements one can observe that there is an alternative odd number of electrons and an even number proofing that that half of the first 18 elements shows paramagnetism and diamagnetism respectively.

Explanation:

3 0
3 years ago
An environmental scientist developed a new analytical method for the determination of cadmium (cd^2+) in mussels. To validate th
Anettt [7]

Answer:

The method is accurate  in the calculation of the Cu^+2

Explanation:

As a first step we have to calculate the <u>average concentration </u>of Cu^+2 find it by the method.

\frac{0.782+0.762+0.825+0.838+0.761 }{5} =0.79 ppm

Then we have to find the<u> standard deviation:</u>

s=\sqrt{\frac{1}{N-1}\sum_{i=1}^N(x_i-\bar{x})^2}=0.0359

For the confidence interval we have to use the formula:

μ=Average±\frac{t*s}{\sqrt{n} }

Where:

t=t student constant with 95 % of confidence and 5 data=2.78

μ= 0.79  ±  \frac{2.78*0.0359}{\sqrt{5} }

upper limit:  0.84

lower limit: 0.75

If we compare the limits of the value obtanied by the method (Figure 1 Red line) with the reference material (Figure 1 blue line) we can see that the values obtained by the method are within the values suggested by the reference material. So, it's method is accurate.

7 0
3 years ago
How much energy do individual photons of 470 nm light have
IceJOKER [234]
<h3>Answer:</h3>

4.227 × 10^-19 Joules

<h3>Explanation:</h3>

Energy of a photon of light is calculated by the formula;

E = hf, where h is the plank's constant, 6.626 × 10^-34 J-s and f is the frequency.

But, f = c/λ

Where, c is the speed of light (2.998 × 10⁸ m/s), and λ is the wavelength.

Given the wavelength is 470 nm or 4.7 × 10^-7 m

Therefore;

E = hc/λ

  = (6.626 × 10^-34 J-s × 2.998 × 10^8 m/s) ÷ 4.7 × 10^-7 m

  = 4.227 × 10^-19 Joules

Therefore, the energy of a photon with 470 nm is 4.227 × 10^-19 Joules

3 0
3 years ago
An original sample of the radioisotope fluorine-21 had a mass of 80.0 milligrams. Only 20.0 milligrams of this original sample r
lyudmila [28]

<u>Answer:</u> The correct answer is Option 3.

<u>Explanation:</u>

All the radioisotope decay processes follow first order kinetics.

Rate law expression for first order kinetics is given by the equation:

k=\frac{2.303}{t}\log\frac{a}{a-x}

where,  

k = rate constant  = ?

t = time taken for decay process = 8.32 seconds

a = initial amount of the reactant  = 80 mg

a - x = amount left after decay process  = 20 mg

Putting values in above equation, we get:

k=\frac{2.303}{8.32sec}\log\frac{80g}{20}\\\\k=0.166sec^{-1}

The equation used to calculate half life for first order kinetics:

t_{1/2}=\frac{0.693}{k}

where,

t_{1/2} = half life of the reaction = ?

k = 0.166sec^{-1}

Putting values in above equation, we get:

t_{1/2}=\frac{0.693}{0.166sec^{-1}}=4.16sec

Hence, the correct answer is Option 3.

5 0
3 years ago
Read 2 more answers
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