<span>this is a limiting reagent problem.
first, balance the equation
4Na+ O2 ---> 2Na2O
use both the mass of Na and mass of O2 to figure out how much possible Na2O you could make.
start with Na and go to grams of Na2O
55.3 gNa x (1molNa/23.0gNa) x (2 molNa2O/4 molNa) x (62.0gNa2O/1molNa2O) = 75.5 gNa2O
do the same with O2
64.3 gO2 x (1 molO2/32.0gO2) x (2 molNa2O/1 mol O2) x (62.0gNa2O/1molNa2O) = 249.2 g Na2O
now you must pick the least amount of Na2O for the one that you actually get in the reaction. This is because you have to have both reacts still present for a reaction to occur. So after the Na runs out when it makes 75.5 gNa2O with O2, the reaction stops.
So, the mass of sodium oxide is
75.5 g</span>
A chemical change affects on the molecular level of matter, which makes it irreversible. Combustion is a pretty good exmple. Physical changes are reversible and dont alter the formula. Hope this helped!
Answer:
An electron is a negatively charged subatomic particle and a proton is a positively charged subatomic particle. Positive charge(s) attract negative charge(s) and vice versa. The proton and neutron stay together and attract one another to give the atom an overall charge of zero (neutral). Which is the charge of an atom. When there is an unequal number of protons and neutrons an ion is formed. If the number of protons are more than the electron, a positively charged ion called cation is formed. On the other hand, if the number of electrons are more than the protons a negatively charged ion called anion is formed.
Answer:

Explanation:
Hello!
In this case, since the standard enthalpy change for a chemical reaction is stood for the enthalpy of reaction, for the given reaction:

We set up the enthalpy of reaction considering the enthalpy of formation of each species in the reaction at the specified phase and the stoichiometric coefficient:

In such a way, by using the NIST database, we find that:

Thus, we plug in the enthalpies of formation to obtain:

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