Fireworks exploding. The trick I use to remember exothermic changes is EXothermic = EXplosion
Answer:
14.04 L.
Explanation:
- The balanced reaction to form Al₂O₃ is:
<em>4Al + 3O₂ → 2Al₂O₃,</em>
4.0 moles of Al react with 3.0 moles O₂ to produce 2.0 moles Al₂O₃.
- Firstly, we need to calculate the no. of moles in (46.54 grams) of Al₂O₃:
<em>n = mass/molar mass </em>= (46.54 g) / (101.96 g/mol) = <em>0.4565 mol.</em>
<em></em>
<u><em>Using cross multiplication:</em></u>
3.0 moles of O₂ produce → 2.0 mole Al₂O₃, from the stichiometry.
??? moles of O₂ produce → 0.4565 mole Al₂O₃.
<em>∴ The no. of moles of O₂ needed to produce 0.4565 mol (46.54 grams) of Al₂O₃</em> = (3.0 mol)(0.4565 mol)/(2.0 mol) = <em>0.6847 mol.</em>
- To calculate the volume of O₂ needed to produce 0.4565 mol (46.54 grams) of Al₂O₃, we can use the general law of ideal gas: <em>PV = nRT.</em>
where, P is the pressure of the gas in atm (P = 1.2 atm).
V is the volume of the gas in L (V = ??? L).
n is the no. of moles of the gas in mol (n = 0.6847 mol).
R is the general gas constant (R = 0.082 L/atm/mol.K),
T is the temperature of the gas in K (T = 300.0 K).
<em>∴ V = nRT/P</em> = (0.6847 mol)(0.082 L/atm/mol.K)(300.0 K)/(1.2 atm) =<em> 14.04 L.</em>
Answer:
Complete ionic: .
Net ionic: .
Explanation:
Start by identifying species that exist as ions. In general, such species include:
- Soluble salts.
- Strong acids and strong bases.
All four species in this particular question are salts. However, only three of them are generally soluble in water: , , and . These three salts will exist as ions:
- Each formula unit will exist as one ion and one ion.
- Each formula unit will exist as one ion and two ions (note the subscript in the formula .)
- Each formula unit will exist as one and two ions.
On the other hand, is generally insoluble in water. This salt will not form ions.
Rewrite the original chemical equation to get the corresponding ionic equation. In this question, rewrite , , and (three soluble salts) as the corresponding ions.
Pay attention to the coefficient of each species. For example, indeed each formula unit will exist as only one ion and one ion. However, because the coefficient of in the original equation is two, alone should correspond to two ions and two ions.
Do not rewrite the salt because it is insoluble.
.
Eliminate ions that are present on both sides of this ionic equation. In this question, such ions include one unit of and two units of . Doing so will give:
.
Simplify the coefficients:
.
Answer:
a. 6.57 cm
b. 8.17 cm
c. 0.80
Explanation:
a. The compound moved from where it was first placed, to a spot 7.57 cm from the bottom of the paper, in other words:
- 7.57 cm - 1.00 cm = 6.57 cm
b. A similar method is made for the solvent:
- 9.17 cm - 1.00 cm = 8.17 cm
c. The Rf of the factor is equal to the <u>distance that the compound moved divided by the distance the solvent moved</u>: