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Basile [38]
3 years ago
13

1. Sometimes scientists need to be able to replicate the results of a scientific experiment. Explain in what situation(s) this w

ould be necessary.
2. Scientific theories can be modified as new information becomes available. Explain the possibility of this happening and why it may change a theory.

3. Using the steps of the scientific method, explain an example of how you use the scientific method in your daily life.

4. Compare and contrast science and pseudoscience. Explain why one is only used in the scientific community to solve problems.

5. Create a number line in your notes using the metric system. What are the base units for the metric system. Which is bigger, a kg or g?
Chemistry
1 answer:
Andrej [43]3 years ago
4 0
I need this also I’m just here for points
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HELP ASAP: Determine the enthalpy change of the following reaction: CH4 + 4Cl2 -> CCl4+ 4HCl 
Annette [7]

Answer:

A

Explanation:

In this question, we are to calculate the enthalpy of change of the reaction. ΔH

To be able to do that, we use the Hess’ law and it involves the subtraction of the summed heat reaction of the reactants from that of the product.

Thus, mathematically, the enthalpy of change of the reaction would be;

[ΔH(CCl4) + 4 ΔH(HCl)] - [ΔH(CH4) + 4 ΔH(Cl2)]

We can see that we multiplied some heat change by some numbers. This is corresponding to the number of moles of that compound in question in the reaction.

Also, for diatomic gases such as chlorine in the reaction above, the heat of reaction is zero.

Thus, we can have the modified equation as follows;

[ΔH(CCl4) + 4 ΔH(HCl)] - [ΔH(CH4)]

Substituting the values we have according to the question, we have;

-95.98 + 4(-92.3) -(-17.9)

= -95.98 - 369.2 + 17.9

= -447.28 KJ/mol

6 0
3 years ago
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
In a chemical reaction, when particle size is reduced, the rate of reaction increases because of increased surface area of the
Nutka1998 [239]

Answer:

option A

for more information, refer to brainly.com/question/13441946

3 0
2 years ago
N:<br> Calculate the mass percent of each element in Na2S.
Goryan [66]

Answer:

NaS2 has two elements within: Sodium & Sulfur.

Basically, the mass percentage of Na2S is:

Sodium = 58.914%

Sulfur = 41.086%

In total, that would equal: 100%.

Explanation:

Well, we know this because Na (Sodium) has 2 atoms & Sodium has no number after it so, that would be an ordinary one atom.

So, knowing that there are more Sodium's than Sulfur, the mass percentage would be higher, than the percentage of Sulfur.

5 0
3 years ago
What is the difference between an atom and a molecule?
Tems11 [23]

Answer:

Molecules are made of atoms.

5 0
4 years ago
Read 2 more answers
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