The answer is 35.9168 grams
Answer:
A. light striking a road and stopping
Explanation:
light is absorbed when it strikes a road and stops. when light hits an object it can either pass through it (refraction), bounce off of it (reflection), or be blocked by it (absorption). when light is absorbed by an object often becomes warmer. this is why a road gets warm in the sun
Answer:
It has 5 neutrons
Explanation:
The fact that it is a neutral atom tells us that the number of electrons and protons is the same:
- The problem tells us there are 4 electrons, thus there are 4 protons.
The average mass of an atom is the sum of the number of protons and the number of neutrons:
- Mass = # Protons + # Neutrons
With the above information in mind we can <u>calculate the number of neutrons</u>:
- 9 amu = 4 Protons + # Neutrons
Answer : The mass of 12.3 moles of helium (He) is, 49.2 grams.
Solution : Given,
Moles of helium = 12.3 moles
Molar mass of helium = 4 g/mole
Formula used :
Therefore, the mass of 12.3 moles of helium (He) is, 49.2 grams.
1) Chemical reaction:
Fe2O3 + 2Al ---> Al2O3 + 2Fe
2) molar ratios
1 mol Fe2O3 : 2Al : 1 mol Al2O3 : 2 mol Fe
3) Convert 15.0 g of iron into moles
atomic mass Fe = 55.8 g/mol
moles = mass in grams / atomic mass = 15.0 g / 55.8 g/mol = 0.269 mol
4) Use proportions to determine the moles of Fe2O3, Al, and Al2O3
a) 1mol Fe2O3 / 2 mol Fe = x / 0.269 mol Fe
x =
=> x = 0.269 mol Fe * 1 mol Fe2O3 / 2 mol Fe = 0.134 mol Fe2O3
b) 2 mol Al / 2 mol Fe = x / 0.269 mol Fe
=> x = 0.269 mol Al
c) 2 mol Fe / 1 mol Al2O3 = 0.269 mol Fe / x
=> x = 0.269 mol Fe * 1 mol Al2O3 / 2 mol Fe
x = 0.134 mol Al2O3
5) Convert moles to grams
a) Fe2O3
molar mass Fe2O3 = 2* 55.8 g/mol + 3*16g/mol = 159.6 g/mol
mass = molar mass * number of moles
mass = 159.6 g/mol * 0.134 mol = 21.4 g
b) Al
atomic mass = 27.0 g/mol
mass = number of moles * atomic mass = 0.269 mol * 27.0 g/mol = 7.26 g
c) Al2O3
molar mass = 2 * 27.0 g/mol + 3*16.0 g/mol = 102.0g/mol
mass Al2O3 = numer of moles * molar mass = 0.134 mol * 102.0 g/mol = 13.7 g
Answers:
21.4 g Fe2O3
7.26 g Al
13.7 g Al2O3