The balanced chemical equation for the complete combustion of c2h2 is: 2c2h2 + 5o2 → 4co2 + 2 h2o how many grams of o2 are required to react with exactly 0.500 mol of c2h2? 1.25 g 20.0 g 40.0 g 25.0 g

Option C

Explanation:

This is a problem of Stechiometry, so, to do this, let's write the equation again:

2C2H2 + 5O2 → 4CO2 + 2 H2O

According to the reaction, we can see that 2 moles of C2H" reacts with 5 moles of O2. So if we have 0.5 moles of C2H2, we only need to calculate the moles of O2 according to the above relation.

If:  moles C2H2/moles O2 = 2/5

Then: 0.5 / moles O2 = 2/5

Solving for moles O2:

2 moles O2 =  5 * 0.5

moles O2 = 5 * 0.5 / 2

moles O2 = 1.25 moles

Now that we have the moles, we can calculate the grams, using the molecular weight of O2, which is 32 g/mol, then the mass:

m = moles O2 * MM

Replacing we have:

m = 1.25 * 32

m = 40 g O2

And this is the mass required to react exactly with the 0.5 moles of C2H2.

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e

1. a)c-14 has two more protons

2. d)they have different numbers of protons, neutrons, and valence electrons; they are all gases at room temperature.

3. c) iron and nickel.