Which of the following is an example of a physical change?

Chemistry

1 answer:

Solnce55 [7]3 years ago

5 0

Answer;

crushing an aluminum soda can

Explanation;

-A physical change is a type of change in which the form of matter (substance) is altered but one substance is not transformed into another different substance. For example, Crushing an aluminium soda can : after crushing can changes its shape, size but it still remain Aluminum so it is a physical change.

-A chemical change is a process where one or more substances are altered into one or more new and different substances.

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Determine the limiting reactant (lr) and the mass (in g) of nitrogen that can be formed from 50.0 g n2o4 and 45.0 g n2h4. some p

Licemer1 [7]

N2O4(l) + 2 N2H4(l) → 3 N2(g) + 4 H2O(g)
1) to calculate the limiting reactant you need to pass grams to moles.
 moles is calculated by dividing mass by molar mass

mass of N2O4: 50.0 g
molar mass of N2O4 = 92.02 g/mol
molar mass of N2H4 = 32.05 g/mol.
mass of N2H4:45.0 g

moles N2O4=50.0/92.02 g/mol= 0,54 mol of N2O4
moles N2H4= 45/32.05 g/mol= 1,40 mol of N2H4

 2)
By looking at the balanced equation, you can see that 1 mol of N2O4 needs 2 moles of N2H4 to fully react . So to react 0,54 moles of N2O4, you need 2x0,54 moles of N2H4 moles
N2H4 needed = 1,08 moles.
You have more that 1,08 moles N2H4, so this means the limiting reagent is not N2H4, it's N2O4. The molecule that has molecules that are left is never the limiting reactant.

3) 1 mol of N2O4 reacting, will produce 3 mol of N2 (look at the equation)
There are 0,54 mol of N2O4 available to react, so how many moles will produce of N2?
1 mol N2O4------------3 mol of N2
0,54 mol N2O4--------x
x=1,62 mol of N2

4) the only thing left to do is convert the moles obtained, to grams.
We use the same formula as before, moles equal to mass divided by molar mass.
$moles= \frac{grams}{molar mass}$ (molar mass of N2= 28)
1,62 mol of N2= mass/ 28
mass of N2= 45,36 grams

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3 years ago

When the isotonic saline solution described in part A is connected to an unknown solution via a semipermeable membrane, the unkn

ozzi

B. The unknown solution had the lower concentration.

Explanation:

Osmosis is a phenomenon in which the molecules of the solvent has a tendency to move through a membrane which is semipermeable from lower concentrated side to the higher concentration side, so that the concentrations on both sides of the membrane must be equal.

So the unknown solution may have lesser concentration than the isotonic solution so that molecules of that solution move from less concentrated side to the more concentrated side, so its level drops.

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3 years ago

What is the formula of sulfurous acid? H2S HSO4 H2SO4 H2SO3

Bas_tet [7]

The correct answer is H2SO3 I took the assignment already

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4 years ago

Whats 2736 +832091 +09281

astra-53 [7]

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One way is to write down all the numbers and add and write down each number.

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3 years ago

Where on earth did people decide they wanted to go many years ago

adell [148]

Answer:

Many years ago, people living on the Earth, desired to go to the outer space.

Explanation:

When man initiate to go outer space:

Many times ago, people used to think about the world out of Earth, the space and the sky. These thoughts generated the idea of thinking and imagining the space and the moon.

The idea turned into a movie by Georges Méliès, which was inspired by a book written by Jules Verne. The movie gave the idea to Konstantin Tsiolkovsky, a Russian man to develop many ideas which were implemented by Russia and America to build airplanes and rockets that we see launching at present.

A small though became an idea which gave birth to a new invention through which people live their dreams of going in the outer space. Incredible!

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