Answer:
2.2 °C/m
Explanation:
It seems the question is incomplete. However, this problem has been found in a web search, with values as follow:
" A certain substance X melts at a temperature of -9.9 °C. But if a 350 g sample of X is prepared with 31.8 g of urea (CH₄N₂O) dissolved in it, the sample is found to have a melting point of -13.2°C instead. Calculate the molal freezing point depression constant of X. Round your answer to 2 significant digits. "
So we use the formula for <em>freezing point depression</em>:
In this case, ΔTf = 13.2 - 9.9 = 3.3°C
m is the molality (moles solute/kg solvent)
- 350 g X ⇒ 350/1000 = 0.35 kg X
- 31.8 g Urea ÷ 60 g/mol = 0.53 mol Urea
Molality = 0.53 / 0.35 = 1.51 m
So now we have all the required data to <u>solve for Kf</u>:
Hey there!
Molar mass N2 = 28.01 g/mol
Therefore:
28.01 g N2 -------------- 6.02*10²² molecules N2
( mass N2 ?? ) ----------- 25,000 molecules N2
mass N2 = ( 25,000 * 28.01 ) / ( 6.02*10²³ )
mass N2 = 700250 / 6.02*10²³
mass N2 = 1.163*10⁻¹⁸ g
Hope that helps!
The activation energy Ea can be related to rate constant (k) at temperature (T) through the equation:
ln(k2/k1) = Ea/R[1/T1 - 1/T2]
where :
k1 is the rate constant at temperature T1
k2 is the rate constant at temperature T2
R = gas constant = 8.314 J/K-mol
Given data:
k1 = 0.543 s-1; T1 = 25 C = 25+273 = 298 K
k2 = 6.47 s-1; T = 47 C = 47+273 = 320 K
ln(6.47/0.543) = Ea/8.314 [1/298 - 1/320]
2.478 = 2.774 *10^-5 Ea
Ea = 0.8934*10^5 J = 89.3 kJ
Answer:
The reaction type is double displacement
<u>Answer:</u> The true statement is iron can reduce 
to gold metal
<u>Explanation:</u>
Single displacement reaction is defined as the reaction in which more reactive element displaces a less reactive element from its chemical reaction.
The reactivity of metal is determined by a series known as reactivity series. The metals lying above in the series are more reactive than the metals which lie below in the series.
Metal A is more reactive than metal B.
We are given:
Iron can reduce copper, silver can reduce gold, sodium can reduce iron and copper can reduce silver metal.
The increasing order of reactivity thus follows:
where, sodium is most reactive and gold is least reactive
For the given options:
<u>Option 1:</u> Copper cannot easily reduce sodium ion to sodium metal because it is less reactive.
<u>Option 2:</u> Iron cant easily reduce gold ion to gold metal because it is more reactive.
<u>Option 3:</u> Silver cannot easily reduce iron ion to iron metal because it is less reactive.
Hence, the true statement is iron can reduce to gold metal
