Answer:
2.95 g of CH₄
Explanation:
To start this, we determine the equation:
4H₂ + CO₂ → CH₄ + 2H₂O
4 moles of hydrogen react to 1 mol of carbon dioxide in order to produce 1 mol of methane and 2 moles of water.
To determine the limiting reactant, we need to know the moles of each reactant.
8.1 g . 1 mol/ 44g = 0.184 moles of carbon dioxide
2.3 g . 1mol / 2g = 1.15 moles of hydrogen
4 moles of hydrogen react to 1 mol of CO₂
Then, 1.15 moles may react to (1.15 . 1) /4 = 0.2875 moles
We only have 0.184 moles of CO₂, so this is the limiting reactant. Not enough CO₂ to complete the 0.2875 moles that are needed.
Ratio is 1:1. 1 mol of CO₂ produces 1 mol of methane
Then, 0.184 moles of CO₂ will produce 0.184 moles of CH₄
We convert moles to mass: 0.184 mol . 16 g /mol = 2.95 g
M(NaCl)=50.0 g
m(H₂O)=150.0 g
m(solution)=m(NaCl)+m(H₂O)
w(NaCl)=100m(NaCl)/m(solution)=100m(NaCl)/{m(NaCl)+m(H₂O)}
w(NaCl)=100*50.0/(50.0+150.0)=25%
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Answer : The correct answer for change in freezing point = 1.69 ° C
Freezing point depression :
It is defined as depression in freezing point of solvent when volatile or non volatile solute is added .
SO when any solute is added freezing point of solution is less than freezing point of pure solvent . This depression in freezing point is directly proportional to molal concentration of solute .
It can be expressed as :
ΔTf = Freezing point of pure solvent - freezing point of solution = i* kf * m
Where : ΔTf = change in freezing point (°C)
i = Von't Hoff factor
kf =molal freezing point depression constant of solvent.
m = molality of solute (m or
)
Given : kf = 1.86 
m = 0.907
)
Von't Hoff factor for non volatile solute is always = 1 .Since the sugar is non volatile solute , so i = 1
Plugging value in expression :
ΔTf = 1* 1.86
* 0.907
)
ΔTf = 1.69 ° C
Hence change in freezing point = 1.69 °C