In 1987 the first substance to act as a superconductor at a temperature above that of liquid nitrogen (77 k) was discovered. the approximate formula of this substance is yba2cu3o7. calculate the percent composition by mass of this material.

The molar mass of the elements are:

Yttrium (Y) = 88.91 g / mol

Barium (Ba) = 137.33 g / mol

Copper (Cu) = 63.55 g / mol

Oxygen (O) = 16 g / mol

Calculating for the molar mass of YBa2Cu3O7:

YBa2Cu3O7 = 88.91 + 2(137.33) + 3(63.55) + 7(16) = 666.22 g / mol

The masses of the elements in 1 mole of YBa2Cu3O7 are:

Yttrium (Y) = 88.91 g / mol (1 mole) = 88.91 g

Barium (Ba) = 137.33 g / mol (2 mole) = 274.66 g

Copper (Cu) = 63.55 g / mol (3 mole) = 190.65 g

Oxygen (O) = 16 g / mol (7 mole) = 112 g

We now calculate for the percent composition by mass of each element:

% Y = 88.91 g / 666.22 g = 13.35%

% Ba = 274.66 g / 666.22 g = 41.23%

%Cu = 190.65 g / 666.22 g = 28.62%

%O = 112 g / 666.22 g = 16.81%

the food using pesticides in the future will harm you by giving you diseases like cancer or something since they have things that we should not eat in it like chemicals or pesticides. that is why organic food is more expensive because they take the time to make it right and healthy for you to eat.

explanation:

nacl or sodium chloride is an ionic compound. this is because an ionic compound pertains to a compound that consists of positively and negatively charged ions. in this case, na (sodium) has a tendency to lose one electron when it reacts with with other atoms, so the resulting sodium ion contains 11 protons and 10 electrons, thus making it positively charged (na+), when chlorine reacts, it usually gains one electron to form an ion called chloride, thus making it negatively charged ( since the ions are oppositely charged, they attract.