Answer:
2.4 g
Explanation:
Step 1: Given data
- Initial pressure (P₁): 755 torr
- Final pressure (P₂): 1.87 atm
Step 2: Convert "P₁" to atm
We will use the conversion factor 1 atm = 760 torr.
755 torr × 1 atm/760 torr = 0.993 atm
Step 3: Convert "T" to K
We will use the following expression.
K = °C + 273.15
K = 25°C + 273.15 = 298 K
Step 4: Calculate the initial number of moles of He
We will use the ideal gas equation.
P₁ × V = n₁ × R × T
n₁ = P₁ × V/R × T
n₁ = 0.993 atm × 16.8 L/(0.0821 atm.L/mol.K) × 298 K
n₁ = 0.682 mol
Step 5: Calculate the final number of moles of He
We will use the ideal gas equation.
P₂ × V = n₂ × R × T
n₂ = P₂ × V/R × T
n₂ = 1.87 atm × 16.8 L/(0.0821 atm.L/mol.K) × 298 K
n₂ = 1.28 mol
Step 6: Calculate the moles of He added
n = n₂ - n₁
n = 1.28 mol - 0.682 mol
n = 0.60 mol
Step 7: Convert "n" to mass
The molar mass of He is 4.00 g/mol
0.60 mol × 4.00 g/mol = 2.4 g
Answer:
105
Explanation:
round 104 to the nearest whole number...since 7 is greater than 5 4 goes up..but if 7 is less than 5,4 remains the same
Answer:
The products are Al(NO₃)₃(aq) and H₂(g).
Al(s) + 3 HNO₃(aq) ⇒ Al(NO₃)₃(aq) + 1.5 H₂(g)
Explanation:
Let's consider the reaction between aluminum and nitric acid. This is a single replacement reaction, in which Al replaces H in HNO₃ to form aluminum nitrate. The unbalanced reaction is:
Al(s) + HNO₃(aq) ⇒ Al(NO₃)₃(aq) + H₂(g)
We start balancing N atoms by multiplying HNO₃ by 3.
Al(s) + 3 HNO₃(aq) ⇒ Al(NO₃)₃(aq) + H₂(g)
Finally, we get the balanced equation multiplying H₂ by 1.5.
Al(s) + 3 HNO₃(aq) ⇒ Al(NO₃)₃(aq) + 1.5 H₂(g)
Answer: non metal
Explanation:
Nonmetals are dull, possess high ionization energies and electronegatives and are typically poor electricity conductors as they're insulators.
Non metals are also brittle and possess low melting point. Therefore, with the explanation, the sample is most likely a non metal.
