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denis23 [38]
3 years ago
5

The mass of solute per 100 mL of solution is abbreviated as (m/v). Mass is not technically the same thing as weight, but the abb

reviation (w/v) is also common. How many grams of sucrose are needed to make 715 mL of a 39.0% (w/v) sucrose solution?
Chemistry
1 answer:
irga5000 [103]3 years ago
4 0

Answer:

Amount of sucrose required = 278.85 g

Explanation:

(w/v)% = 39.0 %

Volume of the solution = 715 mL

39% (w/v) means 39 g of sucrose present in 100 mL of the solution.

Using unitary method,

For making 39% solution,

100 mL solution requires 39 g of the sucrose

therefore, 715 mL solution requires:

                                                715\;mL \times\frac{39\;g}{100\;mL}

                                                = 278.85 g

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Americium-241 is used in smoke detectors. it has a first order rate constant for radioactive decay of k=1.6×10−3yr−1. by contras
Helga [31]
This question is missing the part that actually asks the question. The questions that are asked are as follows:

(a) How much of a 1.00 mg sample of americium remains after 4 day? Express your answer using 2 significant figures.

(b) How much of a 1.00 mg sample of iodine remains after 4 days? Express your answer using 3 significant figures.

We can use the equation for a first order rate law to find the amount of material remaining after 4 days:

[A] = [A]₀e^(-kt)

[A]₀ = initial amount
k = rate constant
t = time
[A] = amount of material at time, t.

(a) For americium we begin with 1.00 mg of sample and must convert time to units of years, as our rate constant, k, is in units of yr⁻¹.

4 days x 1 year/365 days = 0.0110

A = (1.00)e^((-1.6x10^-3)(0.0110))
A = 1.0 mg

The decay of americium is so slow that no noticeable change occurs over 4 days.

(b) We can simply plug in the information of iodine-125 and solve for A:

A = (1.00)e^(-0.011 x 4)
A = 0.957 mg

Iodine-125 decays at a much faster rate than americium and after 4 days there will be a significant loss of mass.
7 0
3 years ago
The picture below shows one cell dividing into two cells.
vitfil [10]

all cells come from pre existing cells


4 0
3 years ago
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What is the sign of enthalpy change for (a), an endothermic reaction? (b). an exothermic reaction?
fenix001 [56]

Answer:

The answer is: (a) positive; (b) negative.

Explanation:

The change in enthalpy (ΔH) of a reaction is the amount of energy absorbed or released during a chemical reaction carried out at constant pressure.

a) In an endothermic chemical reaction, heat energy is absorbed by the system from the surrounding. Therefore, the sign of enthalpy change for an endothermic process is positive, ΔH= positive.

b) In an exothermic chemical reaction, heat energy is released by the system into the surrounding. Therefore, the sign of enthalpy change for an exothermic process is negative, ΔH= negative.

8 0
3 years ago
What is the specific heat of a substance if 1450 calories are required to raise the temperature of a 240g sample by 20℃?
bazaltina [42]

Answer:

6960 J/kg°C

Explanation:

specific heat= mass×specific heat capacity×increase in temperature

specific heat= 0.240×1450×20= 6960 J/kg°C

hope it helps!

5 0
3 years ago
♡
Oksi-84 [34.3K]

Your question has been heard loud and clear.

Both scientific laws and scientific theories are not based on hypothesis.

Because , scientific laws are proven and so they are real not hypothetical.

Whereas scientifc theories can be hypothetical.

Thank you

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3 years ago
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