Hope you understand how to work out those types of questions now xD ;)
Answer:
P = 133.4 atm
Explanation:
Given data:
Mass of helium = 988 g
Volume = 45.0 L
Temperature = 23°C (23+273= 296 K)
Pressure of cylinder = ?
Solution:
Number of moles of helium:
Number of moles = mass/ molar mass
Number of moles = 988 g/ 4 g/mol
Number of moles = 247 mol
Pressure:
PV = nRT
P = nRT/V
P = 247 mol × 0.0821. atm. L/mol. K × 296 K / 45 L
P = 6002.5 / 45 L
P = 133.4 atm
Answer:
7. A) I, II
; 8. D) 2.34e9 kJ
Step-by-step explanation:
7. Combustion of ethanol
I. The negative sign for ΔH shows that the reaction is exothermic.
II. The enthalpy change would be different if gaseous water were produced.
That's because it takes energy to convert liquid water to gaseous water, and this energy is included in the value of ΔH.
III. The reaction is a redox reaction, because
- Oxygen is reacting with a compound
- The oxidation number of C increases
- The oxidation number of O decreases.
IV. The products of the reaction occupy a smaller volume than the reactants, because 3 mol of gaseous reactant are forming 2 mol of gaseous product.
Therefore, only I and II are correct.
7. Hindenburg
Data:
V = 2.00 × 10⁸ L
p = 1.00 atm
T = 25.1 °C
ΔH = -286 kJ·mol⁻¹
Calculations:
(a) Convert temperature to kelvins
T = (25.1 + 273.15) K = 298.25 K
(b) Moles of hydrogen
Use the <em>Ideal Gas Law</em>:
pV = nRT
n = (pV)/(RT)
n = (1.00 × 2.00 × 10⁸)/(0.082 06 × 298.25) = 8.172 × 10⁶ mol
(c) Heat evolved
q = nΔH = 8.172 × 10⁶ × (-286) = -2.34 × 10⁹ kJ
The hydrogen in the Hindenburg released 2.34e9 kJ
.
Answer : The correct option is, (D) double replacement reaction
Explanation :
Synthesis reaction : A chemical reaction where multiple substances or reactants combine to form a single product.
It is represented as,
Decomposition reaction : A chemical reaction in which larger reactant decomposes to give two or more than two products.
It is represented as,
Single replacement reaction : A chemical reaction in which the more reactive element replace the less reactive element.
It is represented as,
In this reaction, A is more reactive element and B is less reactive element.
Double replacement reaction : It is a type of chemical reaction where a positive cation and a negative anion of two reactants exchange places to form two new products.
It is represented as,
(X and A are the cations, Y and B are the anions)
The given reaction is:
This reaction is a double displacement reaction.
Answer:
sp²
Explanation:
You need to look at how many electron orbitals around the atom. Looking at the structure below, you can see that there are three electron orbitals. This gives you an sp² hybridization.
