The volume in liters occupied by 22.6 g of I₂ gas at STP is 1.99 L (answer A)
<u><em>calculation</em></u>
Step: find the moles of I₂
moles= mass÷ molar mass
from periodic table the molar mass of I₂ is 253.8 g/mol
moles = 22.6 g÷253.8 g/mol =0.089 moles
Step 2:find the volume of I₂ at STP
At STP 1 moles =22.4 L
0.089 moles= ? L
<em>by cross multiplication</em>
={ (0.089 moles x 22.4 L) /1 mole} = 1.99 L
Molar mass Pb = 207.2 g/mol
1 mole Pb ------------- 207.2
? mole Pb ------------ 9.51 x 10³
moles = 9.51 x 10³ * 1 / 207.2
moles = 9.51 x 10³ / 207.2
= 45.89 moles
hope this helps!
Answer:
[Ca²⁺] = 1M
[NO₃⁻] = 2M
Explanation:
Calcium nitrate dissociates in water as follows:
Ca(NO₃)₂ ⇒ Ca²⁺ + 2NO₃⁻
The moles of Ca²⁺ can be found using the molar relationship between Ca(NO₃)₂ and Ca²⁺
(0.100mol Ca(NO₃)₂) (Ca²⁺ /Ca(NO₃)₂) = 0.100 mol Ca²⁺
The concentration of Ca²⁺ is then:
[Ca²⁺] = n/V = (0.100mol)/(100.0mL) x (1000ml)/(1L) = 1M
Similarly, moles of NO₃⁻ can be found using the molar relationship between Ca(NO₃)₂ and NO₃⁻:
(0.100mol Ca(NO₃)₂) (2NO₃⁻/Ca(NO₃)₂) = 0.200 mol NO₃⁻
The concentration of NO₃⁻ is then:
[NO₃⁻] = (0.200mol)/(100.0mL) x (1000ml)/(1L) = 2M
<span>The right answer is D. In a situation where the sound wave reaches the ear and the reflected wave reaches the ear less than 0.1 seconds later, the individual would not be able to hear an echo. There needs to a far more significant delay between the sound and the reflection of said sound reaching the listener's ear for the echo effect to become apparent.</span>