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3 years ago

What explains the fact that no machine is 100 percent efficient?

1 answer:

3 0

Hello, to answer your question. It is because all machines require a fuel or source to power it making it imperfect for using some source that may not be renewable.

Signed by, Virtouso Sargedog

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A chemist weighed out 70.8 g of magnesium. Calculate the number of moles of magnesium she weighed out. Round your answer to sign

solniwko [45]

Answer:

2.91 grams of Magnesium

Explanation:

I put a picture . I used the molar mass of magnesium which can be calculated from the periodic table or simply google it. :) I hope it helps - Enrique

8 0

3 years ago

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Which is the correct net ionic equation for the following reaction: H3PO4 (aq) + 3 LiOH (aq) > Li3PO4 (aq) + 3 H2O (l)?

torisob [31]

Answer: The correct option for the chemical equation $H_3PO_4(aq.)+3LiOH(aq.)\rightarrow Li_3PO_4(aq.)+3H_2O(l)$ is 1.

The correct option for the chemical equation $2HBr(aq.)+Co(OH)_2(aq.)\rightarrow CoBr_2(aq.)+2H_2O(l)$ is 3.

Explanation:

For the chemical equation:

$H_3PO_4(aq.)+3LiOH(aq.)\rightarrow Li_3PO_4(aq.)+3H_2O(l)$

$H_3PO_4$ is a weak acid and hence will not dissociate into ions whereas LiOH is a strong base and will easily dissociate into ions.

The product $Li_3PO_4$ is soluble in water and hence, will dissociate into its respective ions. Hence, the ionic equation for this reaction is:

$H_3PO_4(aq.)+3Li^{3+}(aq.)+3OH^-(aq.)\rightarrow 3Li^{3+}(aq.)+PO_4^{3-}(aq.)+3H_2O(l)$

Net ionic equation becomes:

$H_3PO_4(aq.)+3OH^-(aq.)\rightarrow PO_4^{3-}(aq.)+3H_2O(l)$

So, the correct option is 1.

For the chemical equation:

$2HBr(aq.)+Co(OH)_2(aq.)\rightarrow CoBr_2(aq.)+2H_2O(l)$

HBr and $Co(OH)_2$ are strong acid and strong base respectively, hence they will easily dissociate into ions.

The product, $CoBr_2$ is is soluble in water and hence, will dissociate into its respective ions. Hence, the ionic equation for this reaction is:

$2H^+(aq.)+2Br^-(aq.)+Co^{2+}(aq.)+2OH^-(aq.)\rightarrow Co^{2+}(aq.)+2Br^-(aq.)+H_2O(l)$

The net ionic equation becomes:

$H^+(aq.)+OH^-(aq.)\rightarrow H_2O(l)$

So, the correct option is 3.

4 0

2 years ago

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Which of these elements have the same number of valance electrons

solmaris [256]

Both carbon and lead belong to Group IV elements, and thus they have the same number of valence electrons.
In each of the other options, the two elements belong to different groups, and thus they do NOT have the same number of valence electrons.

I hope this helped you, please tell me if I am correct or not <3

6 0

3 years ago

For the following reaction, identify the element that was oxidized, the element that was reduced, and the reducing agent. Give a

Volgvan

For this reaction, oxidation number of Carbon in CO would be +2 while oxidation number of carbon in CO2 would be +4 and so this means that carbon has oxidized. Oxidation number of nitrogen in NO is +2. While oxidation number of nitrogen in N2 is 0 so this means that nitrogen had reduced. The reducing agent is the one which provides electrons by oxidizing itself so in this case; CO is the reducing agent while the C in CO oxidized to produce electrons. I am hoping that this answer has satisfied your query about and it will be able to help you, and if you’d like, feel free to ask another question.

6 0

3 years ago

How many moles of O2 are needed to react with 2.35 mol of C2H2?

Mrrafil [7]

2 C2H2 + 5 O2 --> 4 CO2 + 2 H2O

2.35 mol C2H2 - x mol O2
2 mol C2H2 - 5 mol O2

$x = \frac{2.35 \times 5}{2} = 5.875 \: mol$
answer: 5.875 mol

5 0

3 years ago

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