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love history [14]
3 years ago
10

For light with a wavelength of 12.5 nm, determine the energy of light in kJ/mol

Chemistry
1 answer:
vovikov84 [41]3 years ago
3 0
Energy is related to Wavelength as,

                                   E  =  h c / λ      --------  (1)
As,
       h  =  6.626 × 10⁻³⁴ Js
       c  =  2.99 × 10⁸ ms⁻¹
       λ  =  12.5 nm = 1.25 × 10⁻⁸ m

Putting values in eq. 1,

             E  =  (6.626 × 10⁻³⁴ Js × 2.99 × 10⁸ ms⁻¹) ÷ 1.25 × 10⁻⁸ m

             E  =  1.585 × 10⁻¹⁷ J

             E  =  1.585 × 10⁻²⁰ kJ × 6.022 × 10²³

             E  =  9544.87 Kj/mol
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How many significant digits are there in the measurement 50,600 mg A)4 B)5 C)6 D)7
Arte-miy333 [17]

Five. The measurement 50,600 mg has five significant digits.

I presume that you are using the comma as a decimal separator.

The <em>rules for significant figures</em> are
1. Nonzero digits are always significant.
2. Any zeros between two significant digits are significant.
3. Final or trailing zeros are significant only if they are to the right of a decimal point.

• According to Rule 1, the <em>5 and 6</em> are significant.
• According to Rule 2, the <em>0 between the 5 and 6</em> is significant
• According to Rule 3, the <em>final two zeros</em> are significant.

Thus, there are five significant digits in the measurement 50,600 mg.

Note: If the comma is a thousands separator, the number has only three significant digits.

7 0
3 years ago
Read 2 more answers
If you start with 227.8 grams of iron and 128 grams of oxygen to produce iron oxide, what is the limiting reagent?
agasfer [191]

The balanced chemical equation between iron and oxygen to produce iron (III) oxide is,

4Fe(s) + 3O_{2}(g) ---> 2Fe_{2}O_{3}(s)

Mass of Fe = 227.8 g

Moles of Fe = 227.8 g Fe * \frac{1 mol Fe}{55.85 g Fe} = 4.079 mol Fe

Mass of oxygen = 128 g

Moles of O_{2} = 128 g O_{2}*\frac{1 mol O_{2}}{32 g O_{2}}= 4mol O_{2}

Calculating the limiting reactant: The reactant that produces the least amount of product will be the limiting reactant.

Mass of iron (III) oxide produced from Iron = 4.079 mol Fe * \frac{2 mol Fe_{2}O_{3}}{4 mol Fe}  *\frac{159.69 g Fe_{2}O_{3}}{1 mol Fe_{2}O_{3}} = 325.7 g Fe_{2}O_{3}

Mass of iron (III) oxide produced from oxygen=4 mol O_{2}*\frac{2 molFe_{2}O_{3}}{3 mol O_{2}}*\frac{159.69 g Fe_{2}O_{3}}{1 mol Fe_{2}O_{3}} =  425.84 g Fe_{2}O_{3}

Iron (Fe) produces the least amount of the product iron (III) oxide. So, Fe is the limiting reactant.

7 0
3 years ago
SOMEONE HELP ASAPP...
saveliy_v [14]

AnswU GOT THIS!!!!!!!!!!!!!

Explanation:

4 0
3 years ago
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The chemical equation, Cr + Fe(NO3)2 → Fe + Cr(NO3)3, is an example of which type of reaction?
Angelina_Jolie [31]

Answer:

Redox type

Explanation:

The reaction is:

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2 moles of chromium can react to 3 moles of iron (II) nitrate in order to produce 2 moles of iron and 2 moles of chromium nitrate.

If we see oxidation state, we see that chromium changes from 0 to +3

Iron changed the oxidation state from +2 to 0

Remember that elements at ground state has 0, as oxidation state.

Iron is being reduced while chromium is oxidized. Then, the half reactions are:

Fe²⁺  +  2e⁻ ⇄  Fe    (Reduction)

Cr ⇄ Cr³⁺  +  3e⁻    (Oxidation)

When an element is being  reduced, while another is being oxidized, we are in prescence of a redox reaction.

8 0
3 years ago
Describe a polyhydroxyl alcohol.
Mademuasel [1]
With a name like poly hydroxyl alcohol, it suggests that the alcohol has more than one alcohol group. Thus any alcohol with more than one hydroxyl is a polyhydroxyl alcohol. An example that pops into mind is ethanediol (CH2OHCH2OH) this has 2 hydroxyl groups and is an alcohol, thus a polyhydroxyl alcohol
8 0
3 years ago
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