When dealing with making diluted solutions from concentrated solutions, we can use the following formula
c1v1 = c2v2
where c1 and v1 are the concentration and volume of the concentrated solution respectively.
c2 and v2 are the concentration and volume of the diluted solution respectively
substituting these values in the above formula,
20 mL x 0.200 M = C x 250.0 mL
C = 0.0160 M
You got the questions correct
Answer:
moles
Explanation:
The reaction equation is given as:
4NH₃ + 5O₂ → 4NO + 6H₂O
The number of moles of O₂ that completely reacted is given as 1 mole
To solve this problem, we are going to use a stoichiometric approach from the balanced reaction equation:
5 moles of O₂ will react completely to produce 4 moles of NO
1 mole of O₂ will therefore react to produce x mole of NO
5x = 4
x = moles of NO
Explanation:
A change that does not cause any change in chemical composition of a substance is known as a physical change.
For example, mass, density, volume etc are all physical changes.
On the other hand, a change that brings change in chemical composition of a substance is known as chemical change.
For example, combustion, toxicity, reactivity etc are all chemical changes.
Hence, following statements are identified as chemical or physical changes as follows.
(a) Oxygen gas supports combustion : Chemical change
(b) Fertilizers help to increase agricultural production : Chemical change
(c) Water boils below on top of a mountain : Physical change
(d) Lead is denser than aluminum : Physical change
(e) Uranium is a radioactive element : Chemical change