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BARSIC [14]
3 years ago
12

A sample is in the second half-life. What percent of the sample is stable at this point?

Chemistry
1 answer:
Kruka [31]3 years ago
8 0

Answer:

75%

Explanation:

on edg :)

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450g of chromium(iii) sulfate reacts with excess potassium phosphate. How many grams of potassium sulfate will be produced? (ANS
Irina18 [472]

Answer:

600 g K₂SO₄

Explanation:

First write down the complete, balanced chemical equation for such question. In this case:

Cr₂(SO₄)₃ + 2K₃PO₄ →  3K₂SO₄ + 2CrPO₄

Next, calculate molar masses of required compounds mentioned in the question. In this case it is for Cr₂(SO₄)₃ and K₂SO₄.

  • Molar mass(MM) of Cr₂(SO₄)₃:

        = 2*(MM of Cr) + 3*( MM of S) + 3*4*( MM of O)

        = 2*(52) + 3*(32) + 12*(16)

        = 104 + 96 + 192

        = 392 g

  • Molar mass(MM) of K₂SO₄:

        = 2*(MM of K) + 1*( MM of S) + 4*( MM of O)

        = 2*(39) + 32 + 4*(16)

        = 78 + 32 + 64

        = 174 g

Here comes the concept of Limiting reagent:

The limiting reagent in a chemical reaction is the substance that is totally consumed when the chemical reaction is complete. The amount of product formed is limited by this reagent, since the reaction cannot continue without it. The other reactants present with this are usually in excess and called excess reactants. If quantities of both the reactants are given, then one should apply unitary method and find out the limiting reagent out of the two. Then, determine the amount of product formed or percentage yield.

Also, 1 mole( 392 g) of Cr₂(SO₄)₃ gives 3 moles( 174*3 = 522 g) of K₂SO₄.

Using unitary method, if 392g of Cr₂(SO₄)₃ gives 522 g of K₂SO₄ , then 450 g of Cr₂(SO₄)₃ will give how much of K₂SO₄?

Yeild of K₂SO₄ : \frac{522 * 450}{392}

That is 599.3 g.

Since we have not considered molecular masses of individual atoms to 6 decimal places, this number can be approximated to 600g.

Therefore, 600g of K₂SO₄ is produced.

6 0
3 years ago
In the polypeptide Phe-Tyr-Glu-Asp-Ser-Ile-Leu-Ser what is the N-terminal amino acid?
avanturin [10]

Answer:

N-terminal Phe, C-terminal Ser

Explanation:

Amino acids connect like

NH2 -CH(R1) -CO -NH-CH(R2)-CO-.....-NH-CH(Rn)COOH

So, 1st amino acid is N -terminal , and it is Phe.

Last amino acid is C- terminal, and it is Ser.

7 0
3 years ago
As part of her nuclear stress test, Simone starts to walk on the treadmill. When she reaches the maximum level, Paul injects a r
Naya [18.7K]

Answer:

Part A: 36 MBq; Part B: 18 MBq

Explanation:

The half-life is the time it takes for half the substance to disappear.

The activity decreases by half every half-life

A =Ao(½)^n, where n is the number of half-lives.

Part A

3.0 da = 1 half-life

A =  Ao(½) = ½ × 72 MBq = 36 MBq

Part B

6.0 da = 2 half-lives

A = Ao(½)^2 = ¼ × 72 MBq = 18 MBq

3 0
3 years ago
Which of these elements has physical and chemical properties most similar to silicon (Si)?
siniylev [52]
In order from most to least similar:
1. Germanium
2. Lead
3. Phosphorus
4. Chlorine
The elements in the same column as the element you have are the most similar. The rows are not. For example, though chlorine and magnesium are in the same row, they have very different properties, whereas chlorine and fluorine more similar
6 0
3 years ago
Read 2 more answers
Please help me with this chemistry
Elena-2011 [213]

Answer: gasoline, water, sea water, chloroform and mercury so B

Explanation:

6 0
3 years ago
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