How much of strontium-90 will be left after 40 hours if you start with 960 grams and the half-life is 10 hours?

Goshia [24]

The answer for this question is 0.8

8 0

3 years ago

How does the law of conservation of mass relate to the number of atoms of each element that are present before a reaction vs. th

TiliK225 [7]

The law of conservation of mass or principle of mass conservation states that for any system closed to all transfers of matter and energy, the mass of the system must remain constant over time, as system's mass cannot change, so quantity cannot be added nor removed. Hence, the quantity of mass is conserved over time.

The law implies that mass can neither be created nor destroyed, although it may be rearranged in space, or the entities associated with it may be changed in form. For example, in chemical reactions, the mass of the chemical components before the reaction is equal to the mass of the components after the reaction. Thus, during any chemical reaction and low-energy thermodynamic processes in an isolated system, the total mass of the reactants, or starting materials, must be equal to the mass of the products.

According to the Law of Conservation, all atoms of the reactant(s) must equal the atoms of the product(s).
As a result, we need to balance chemical equations. We do this by adding in coefficients to the reactants and/or products. The compound(s) itself/themselves DOES NOT CHANGE.

6 0

2 years ago

What evidence from the experiment shows that conduction occurred? In your answer, be sure to include the materials involved in t

velikii [3]

Answer:

Explanation:

The melting of the chocolate pieces one by one showed that it was caused by heat flowing through the foil bridge. The transfer of heat happened between the foil bridge and the chocolate pieces because they were touching each other.

5 0

2 years ago

Read 2 more answers

Be sure to answer all parts. Nitric oxide, NO·, is a radical thought to cause ozone destruction by a mechanism similar to that o

SIZIF [17.4K]

Answer:

See image attached and explanation

Explanation:

The stratospheric ozone layer is very important in absorbing high-energy ultraviolet radiation that is harmful to living systems on earth. The concentration of ozone in the stratosphere is determined by both thermal and photochemical pathways for its decomposition. Nitric oxide, NO, is a trace constituent in the stratosphere that reacts with ozone to form nitrogen dioxide, NO2, and the diatomic oxygen molecule. The nitrogen-oxygen bond in NO2 is relatively weak. When an NO2 molecule encounters an oxygen atom, it transfers an oxygen, forming O2 and NO. The chemical reactions involved are formations of NO2 following by reaction of NO2 with atomic oxygen for form NO and O2. The sum of both reactions show that the overall reaction is simply the reaction of ozone with atomic oxygen to form two molecules of molecular oxygen. Hence, NO only serves as a catalyst, it does not undergo a permanent change itself.

6 0

2 years ago

Someone please do this!!!

Lilit [14]

Answer:

1) Fe = 69.9%

O = 31.1%

2) H = 5.19%

O = 16.5%

N = 28.9%

C = 49.5%

Explanation:

One easy way to do percent compositions is to assume you have 100g of a substance.

1) Lets say we have 100g of Fe2O3.

The total molar mass would be:

$= 55.845*2+15.999*3 = 159.687$

The molar mass of the Fe2 alone is:

$=55.845*2 = 111.69$

Thus, the grams of Fe2(out of a 100) could be calculated by multiplying 100g * the molar mass ratio of Fe2 to the whole:

$= 100g *\frac{111.69}{159.687} = 69.9431$

Which is approximately 69.9%.

We can find the amount of O3 by simply subtracting, as the rest of the compound is made of O3. Thus, the % composition of O3 is 31.1%

You can then do this same process to the next question, getting us the following:

H = 5.19%

O = 16.5%

N = 28.9%

C = 49.5%

4 0

2 years ago