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lukranit [14]
3 years ago
7

What do scientists use molecular clocks to estimate?

Chemistry
1 answer:
astra-53 [7]3 years ago
4 0

I think the answers B

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what would be the final volume when 2.20 M solution is made from 25.0 mL of a 12.0 M solution? plzz show work
cupoosta [38]

Answer:

136.36 mL

Explanation:

Here we have to use the dilution formula

From C1V1= C2V2

Where;

C1= initial concentration of the solution= 12.0 M

C2= final concentration of the solution= 2.20 M

V1 = initial volume of the solution= 25.0 ml

V2= final volume of the solution= ?????

Then recall;

C1V1=C2V2

V2 = C1V1/C2

Substituting values from the parameters given;

V2= 12.0 × 25.0 / 2.20

V2= 136.36 mL

7 0
3 years ago
In a reaction, 25 grams of reactant
Vsevolod [243]

Answer:

D. 15g

Explanation:

The law of conservation of mass states that, in a chemical reaction, mass can neither be created nor destroyed. This means that the amount of matter in the elements of the reactants must be equal to the amount in the resulting products.

In this question, 25 grams of a reactant AB, was broken down in a reaction to produce 10 grams of products A and X grams of product B. According to the law of conservation of mass, the mass of the reactant must be equal to the total mass of the products. This means that 25 grams must also be the total mass of both products in this reaction. Hence, if product A is 10 grams, product B will be 25 grams - 10 grams = 15 grams.

Therefore, product B must be 15 grams in order to form a total of 25 grams when added to the mass of product A. This will equate the mass of the reactant AB and fulfill the law of conservation of mass.

8 0
4 years ago
Una teoría puede estar respaldada por pruebas considerables.?????
AlladinOne [14]
Respuesta:

Yes.

Explicación:


Las teorías se pueden mejorar o modificar a medida que se recopila más información para que la precisión de la predicción sea mayor con el tiempo.
6 0
3 years ago
3. A student adds 0.400g of n-propanol to 13.0 g of t-butanol. What is the molality of the solution? Show your calculations. (3
marissa [1.9K]

Answer:

m=0.512m

Explanation:

Hello,

In this case, we can consider the n-propanol as the solute (lower amount) and the t-butanol as the solvent (higher amount), for which, initially, we must compute the moles of n-propanol (molar mass = 60.1 g/mol) as shown below:

n_{solute}=0.400g*\frac{1mol}{60.1g0}=6.656x10^{-3}mol

Since the molality is computed via:

m=\frac{n_{solute}}{m_{solvent}}

Whereas the mass of the solvent is used in kilograms (0.0130g for the given one). Thus, we compute the resulting molality of the solution:

m=\frac{6.656x10^{-3}mol}{0.0130kg}\\ \\m=0.512\frac{mol}{kg}

Or just:

m=0.512m

Best regards.

8 0
3 years ago
In this experiment you will create solutions with different ratios of ethanol and water. What is the mole fraction of ethanol wh
Andrej [43]

Answer:

The mole fraction of ethanol is 0.6. A 10 mL volumetric pipette must be used for to measure the 10 mL of ethanol. The vessel should be clean and purged.

Explanation:

For calculating mole fraction of ethanol, the amount of moles ethanol must be calculated. Using ethanol density (0.778 g/mL), 10 mL of ethanol equals to 7.89 g of ethanol and in turn 0.17 moles of ethanol. The same way for calculate the amount of water moles (ethanol density=0.997 g/mL). 2 mL of water correspond to 0.11. The total moles are: 0.17+0.11=0.28. Mole fraction alcohol is: 0.17/0.28=0.6

5 0
3 years ago
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