Answer:
b. 11.90 Liters
Explanation:
- The balanced equation for the mentioned reaction is:
<em>3O₂ + 4Al → 2Al₂O₃,</em>
It is clear that 3.0 moles of O₂ react with 4.0 moles of Al to produce 2.0 Al₂O₃.
- Firstly, we need to calculate the no. of moles (n) of 36.12 g of Al₂O₃:
<em>n = mass/molar mass</em> = (44.18 g)/(101.96 g/mol) = <em>0.4333 mol.</em>
<u><em>using cross multiplication:</em></u>
3.0 mol of O₂ produces → 2.0 mol of Al₂O₃.
??? mol of O₂ produces → 0.4333 mol of Al₂O₃.
<em>∴ The no. of moles of O₂ needed to produce 36.12 grams of Al₂O₃</em> = (3.0 mol)(0.4333 mol)/(2.0 mol) = <em>0.65 mol.</em>
- Now, we can find the volume of O₂ used during the experiment:
We can use the general law of ideal gas: <em>PV = nRT.</em>
where, P is the pressure of the gas in atm (P = 1.3 atm).
V is the volume of the gas in L (V = ??? L).
n is the no. of moles of the gas in mol (n = 0.65 mol).
R is the general gas constant (R = 0.0821 L.atm/mol.K),
T is the temperature of the gas in K (T = 290 K).
<em>∴ V = nRT/P </em>= (0.65 mol)(0.0821 L.atm/mol.K)(290 K)/(1.3 atm) = <em>11.9 L.</em>
<em>So, the right choice is: b. 11.90 Liters.</em>
Answer:
1.24 L of H₂ at STP .
Explanation:
2Al(s) +6HCl(aq) → 2AlCl₃(aq) + 3H₂(g)
2 moles 3 x 22.4 L
2 x 27 g of Al reacts to give 3 x 22.4 L of H₂ at STP .
1 g of Al will react to give 3 x 22.4 / ( 2 x 27 ) L of H₂ at STP .
= 1.24 L of H₂ at STP .
Answer: Since k2 corresponds to 64 hours, the time for the milk to sour at 40 C is 64 h / 9.38 = 6.8 hours.
Explanation:
At temperature T1, the Arrhenius Equation is:
k1 = Ae^(-Ea/RT1).
An equivalent equation can be written at T2:
k2 = Ae^(-Ea/RT2).
If these equations are divided, then A cancels:
k1/k2 = e^(-Ea/RT1)/e^(-Ea/RT2)
Taking the natural log:
ln(k1/k2) = (Ea/RT2)-(Ea/RT1);
or:
ln(k1/k2) = (Ea/R)(1/T2 - 1/T1)
We can infer from the question that the milk sours 3 times as fast at the higher temperature (let's call it T1), so we can arbitrarily call k2 = 1 and k1 = 3.
a) Substitute:
ln(3) = (Ea/R)(1/276.15 K - 1/293.15 K).
We get Ea/R = 5231.6. Multiply this by whatever value of R you choose to get Ea in your favorite energy unit. Remember the sig figs.
b) Again, let's let the lower temperature = T2, since we have defined k2 = 1:
ln(k1) = (5231.6)(1/276.15 K - 1/313.15);
ln(k1) = 2.24, so k1 = 9.38.
Since k2 corresponds to 64 hours, the time for the milk to sour at 40 C is 64 h / 9.38 = 6.8 hours.
Answer:
A
Explanation:
Malleability describes the property of a metal's ability to be distorted below compression. It is a physical property of metals by which they can be hammered, shaped and rolled into a very thin sheet without rupturing. A soda can's walls are very thin, and therefore express the malleability of aluminum.
Heat
gained in a system can be calculated by multiplying the given mass to the
specific heat capacity of the substance and the temperature difference. It is
expressed as follows:<span>
Heat = mC(T2-T1)
When two objects are in contact, it should be that the heat lost is equal to what is gained by the other. From this, we can calculate things. We do as follows:
</span>Heat gained = Heat lost
mC(T2-T1) = - mC(T2-T1)
31.5C (102.4 - 32.5) = 103.5(4.18)(32.5 - 24.5)
C = 1.57 J/C-g
Hope this helps.