Answer:
d. 97.60 g
Explanation:
Given parameters:
Number of moles of formaldehyde = 3.25moles
Ratio:
C H O
1 2 1
Unknown:
Mass of this sample = ?
Solution:
The empirical formula of a compound is its simplest formula. It is the simplest whole number ratio of the atoms in a given substance.
The molecular formula is the actual formula of the compound.
Since the molecular and empirical formula are the same here, the formula of the compound is;
CH₂O
To find the mass of the formaldehyde, use the expression below;
Mass = number of moles x molar mass
molar mass of CH₂O = 12 + 2(1) + 16 = 30g/mol
Mass = 3.25 x 30 = 97.5g
In the first shell there is 2 electrons and on the second shell there is 4 elections.
Answer:
it has a huge electronegativity difference between it's atoms
Answer:
D. -120.9 kJ
Explanation:
According to Hess's law ,the total enthalpy change for a reaction is the sum of all changes regardless of the stages or the steps of the reaction.
....(1)
(this reaction should be reversed in order to reach the required reaction )
On reversing the reaction the sign of 
get reversed.
(In this case change sign from '-' to'+'. Hence = + 65 kJ)
....(1)
......(2)
Adding equation (1) and (2)
![Ca(OH)_{2} + 2HCl \rightarrow CaCl_{2} + 2H_{2}O[tex][tex]Delta H = - 186 + 65 = - 121\kJ](https://tex.z-dn.net/?f=%3Cstrong%3ECa%28OH%29_%7B2%7D%20%2B%202HCl%20%5Crightarrow%20CaCl_%7B2%7D%20%2B%202H_%7B2%7DO%3C%2Fstrong%3E%5Btex%5D%3C%2Fp%3E%3Cp%3E%5Btex%5D%3Cstrong%3EDelta%20H%20%3D%20-%20186%20%2B%2065%20%3D%20-%20121%5CkJ%3C%2Fstrong%3E)
(It is nearly equal to -120.9 kJ)
Answer:
Explanation: We all learn at school that pure water always boils at 100°C (212°F), under normal atmospheric pressure. ... And removing dissolved air from water can easily raise its boiling temperature by about 10 degrees centigrade.
