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:
A. 0.0655 mol/L.
B. PbBr2.
C. Pb2+(aq) + Br- --> PbBr2(s).
Explanation:
Balanced equation of the reaction:
Pb(NO3)2(aq) + 2NaBr(aq) --> PbBr2(s) + 2NaNO3(aq)
A.
Number of moles
PbBr2
Molar mass = 207 + (80*2)
= 367 g/mol.
Moles = mass/molar mass
= 3.006/367
= 0.00819 mol.
Since 2 moles of NaBr reacted to form 1 mole of PbBr2. Therefore, moles of NaBr = 2*0.00819
= 0.01638 moles of NaBr.
Since, the ionic equation is
NaBr(aq) --> Na+(aq) + Br-(aq)
Since 1 moles of NaBr dissociation in solution to give 1 mole of Br-
Therefore, molar concentration of Br-
= 0.0164/0.25 L
= 0.0655 mol/L.
B.
PbBr2
C.
Pb(NO3)2(aq)--> Pb2+(aq) + 2No3^2-(aq)
2NaBr(aq) --> 2Na+(aq) + 2Br-(aq)
Net ionic equation:
Pb2+(aq) + 2Br- --> PbBr2(s)
Answer:
C. Water will move from solution A to solution B because glucose is in higher concentration.
Explanation:
In osmosis, the molecules of solvent will pass through a semipermeable membrane from a less concentrated to a more concentrated solution.
Solution B is more concentrated, so the water will move from A to B.
A and D are wrong, because the size of the solute particles does not control the direction of osmosis.
B is wrong because water moves to the more concentrated solution.
Answer : The final volume at STP is, 1000 L
Explanation :
According to the Boyle's, law, the pressure of the gas is inversely proportional to the volume of gas at constant temperature and moles of gas.
or,
where,
= initial pressure = 1520 mmHg = 2 atm (1 atm = 760 mmHg)
= final pressure at STP = 1 atm
= initial volume = 500.0 L
= final volume at STP = ?
Now put all the given values in the above formula, we get:
Therefore, the final volume at STP is, 1000 L
