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Degger [83]
3 years ago
14

I need help! how many moles are in 3.4*10^-7 grams of silicon dioxide, SiO2. I got 2.0^17 but I think it's wrong :(

Chemistry
1 answer:
blondinia [14]3 years ago
8 0
Molar mass SiO2 = 28 + 32 = 60 

<span>so moles sand = 3.4 x 10-7 / 60</span>
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Số oxi hoá của nitơ trong NH3, H2SO4, NO3 lần lượt là:
NikAS [45]

Answer:

3,6,6...................................

6 0
3 years ago
If you observe with the microscope that a cell contains chloroplasts can you conclude that this is a plant cell?
shusha [124]
Obviously since plant cell contains chloroplasts.
8 0
3 years ago
Indicate the peptides that would result from cleavage by the indicated reagent: a. Gly-Lys-Leu-Ala-Cys-Arg-Ala-Phe by trypsin b.
Ilia_Sergeevich [38]

Answer:

a. Gly-Lys + Leu-Ala-Cys-Arg + Ala-Phe

b. Glu-Ala-Phe + Gly-Ala-Tyr

Explanation:

In this case, we have to remember which peptidic bonds can break each protease:

-) <u>Trypsin</u>

It breaks selectively the peptidic bond in the carbonyl group of lysine or arginine.

-) <u>Chymotrypsin</u>

It breaks selectively the peptidic bond in the carbonyl group of phenylalanine, tryptophan, or tyrosine.

With this in mind in "peptide a", the peptidic bonds that would be broken are the ones in the <u>"Lis"</u> and <u>"Arg"</u> (See figure 1).

In "peptide b", the peptidic bond that would be broken is the one in the <u>"Phe"</u> (See figure 2). The second amino acid that can be broken is <u>tyrosine</u>, but this amino acid is placed in the <u>C terminal spot</u>, therefore will not be involved in the <u>hydrolysis</u>.

3 0
3 years ago
Which of the following observations likely describes a physical change?
Inessa05 [86]

Answer:

The answer is evaporation

4 0
3 years ago
30.5 g of sodium metal reacts with chlorine gas to produce sodium chloride. How much (in grams) chlorine gas must react with thi
Lena [83]

Answer:

Mass of chlorine = 47.22 g

Explanation:

Given data:

Mass of sodium = 30.5 g

Mass of chlorine= ?

Solution:

Chemical equation:

 2Na + Cl₂      →      2NaCl  

Number of moles of Na:

Number of moles = mass/molar mass

Number of moles = 30.5g/ 23 g/mol

Number of moles = 1.33 mol

Now we will compare the moles of Cl ₂ with Na from balance chemical equation.

                    Na            :              Cl ₂

                     2              :               1

                     1.33          :            1/2×1.33 = 0.665 mol

Mass of chlorine gas:

Mass = number of moles × molar mass

Mass = 0.665 mol × 71 g/mol

Mass = 47.22 g

6 0
3 years ago
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