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3 years ago

An early version of the Periodic Table had the elements listed in order of increasing relative atomic

Chemistry

2 answers:

Misha Larkins [42]3 years ago

8 0

I really agree with the other comment

ser-zykov [4K]3 years ago

4 0

Answer:

Although he was unaware ofit, Mendeleev had actually placed the elements inorder of increasing “atomic number,” a numberrepresenting the amount of positively charged protons in the atom (also thenumber of negatively charged electronsthat orbit the atom). Mendeleev went even further.

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At a wastewater treatment plant, FeCl3(s) is added to remove excess phosphate from the effluent. Assume the following reactions

RoseWind [281]

Answer : The concentration of $Fe^{3+}$ needed is, $2.37\times 10^4M$

Explanation :

First we have to calculate the mole of phosphate.

As we are given that, 1 mg P/L that means, 1 mg of phosphate present in 1 L of solution.

$\text{Moles of phosphate}=\frac{\text{Mass of phosphate}}{\text{Molar mass of phosphate}}$

Molar mass of phosphate = 94.97 g/mole

$\text{Moles of phosphate}=\frac{1mg}{94.97g/mol}=\frac{0.001g}{94.97g/mol}=1.053\times 10^{-5}mol$

Now we have to calculate the concentration of phosphate.

$\text{Concentration of phosphate}=\frac{\text{Moles of phosphate}}{\text{Volume of solution}}$

$\text{Concentration of phosphate}=\frac{1.053\times 10^{-5}mol}{1L}=1.053\times 10^{-5}mol/L$

Now we have to calculate the concentration of $Fe^{3+}$ .

The second equilibrium reaction is,

$FePO_4\rightleftharpoons Fe^{3+}+PO_4^{3-}$

The solubility constant expression for this reaction is:

$K_{sp}=[Fe^{3+}][PO_4^{3-}]$

Given: $K_{sp}=\frac{1}{4}$

$\frac{1}{4}=[Fe^{3+}]\times 1.053\times 10^{-5}mol/L$

$[Fe^{3+}]=2.37\times 10^4M$

Thus, the concentration of $Fe^{3+}$ needed is, $2.37\times 10^4M$

8 0

4 years ago

What causes damage to the ozone layer?

ryzh [129]

<span>Chlorofluorocarbons (CFCs) can damage the ozone layer.</span>

3 0

3 years ago

Read 2 more answers

A turbine operates on superheated steam that enters at 80 bar absolute and 500˚C, and leaves the turbine at 7.5 bar absolute and

yanalaym [24]

The answer is

d. To what temperature can the steam at 80 bar be cooled before a liquid will appear?

6 0

4 years ago

If the initial volume is 55ml and the final volume after some rocks of sandstone are added is 65ml what is the volume of the chi

AfilCa [17]

Answer:

Volume = 10ml

Density = 1/5 g/ml or 0.20g/ml

Explanation:

The rocks are 10ml since the initial volume went up by 10.

Since density = mass/volume, you divide 2 by 10.

D = 2/10

D = 1/5 g/ml or 0.20g/ml

(Unit is g/ml aka grams/millileter)

7 0

3 years ago

What is required in order for heat to transfer between two objects & then how does it move

AleksAgata [21]

Two objects at different temperatures are in contact with each other. Heat flows from the warmer to the cooler object until they are both at the same temperature. The answer is C

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3 years ago