Answer:
In order to react with 45 g of water 1.25 moles of CaC₂ are required.
Explanation:
Given data:
Moles of CaC₂ needed = ?
Mass of water = 45.0 g
Solution:
Chemical equation:
CaC₂ + 2H₂O → C₂H₂ + Ca(OH)₂
Number of moles of water:
Number of moles = mass/ molar mass
Number of moles = 45 g/ 18 g/mol
Number of moles = 2.5 mol
Now we will compare the moles of water and CaC₂ from balance chemical equation:
H₂O : CaC₂
2 : 1
2.5 : 1/2×2.5 =1.25 mol
In order to react with 45 g of water 1.25 moles of CaC₂ are required.
Here we will use the general formula of Nernst equation:
Ecell = E°Cell - [(RT/nF)] *㏑Q
when E cell is cell potential at non - standard state conditions
E°Cell is standard state cell potential = - 0.87 V
and R is a constant = 8.314 J/mol K
and T is the temperature in Kelvin = 73 + 273 = 346 K
and F is Faraday's constant = 96485 C/mole
and n is the number of moles of electron transferred in the reaction=2
and Q is the reaction quotient for the reaction
SO42-2(aq) + 4H+(aq) +2Br-(aq) ↔ Br2(aq) + SO2(g) +2H2O(l)
so by substitution :
0 = -0.87 - [(8.314*346K)/(2* 96485)*㏑Q → solve for Q
∴ Q = 4.5 x 10^-26
<span>The mass (in grams) of 8.45 x 10^23 molecules of dextrose is 252.798g
Working:
Mw. dextrose is 180.16 g/mol
therefore 180.16 grams dextrose = 1 mole
therefore 180.16 grams dextrose= 6.022x10^23 molecules (Avogadro's number)
We have 8.45 x 10^23 molecules of dextrose.
Therefore, (180.16 divided by 6.022x10^23) times 8.45x10^23
gives the mass (in grams) of 8.45 x 10^23 molecules of dextrose;
252.798.</span>
Here we have to get the right answers which include the given phrase.
The correct answers are as following:
High boiling and melting points: Hydrogen bond increase the amount of energy required for phase changes to occur, thereby raising the boiling and melting points.
High specific heat: Hydrogen bond increase the amount of energy required for molecules to increase the speed, thereby raising the specific heat.
High surface tension: Hydrogen bonds produce strong inter molecular attractions, which increase surface tension.
The incorrect answer:
Lower density as a solid than as a liquid: actually, density of solid is more than density of liquid as hydrogen bonds in solid produce strong inter molecular attractions among molecules, which aggregates molecules together, hence volume of associated molecules reduces. Therefore, density of solid is more than that of liquid.
