Answer:
All of the above processes have a ΔS < 0.
Explanation:
ΔS represents change in entropy of a system. Entropy refers to the degree of disorderliness of a system.
The question requests us to identify the process that has a negative change of entropy.
carbon dioxide(g) → carbon dioxide(s)
There is a change in state from gas to solid. Solid particles are more ordered than gas particles so this is a negative change in entropy.
water freezes
There is a change in state from liquid to solid. Solid particles are more ordered than liquid particles so this is a negative change in entropy.
propanol (g, at 555 K) → propanol (g, at 400 K)
Temperature is directly proportional to entropy, this means higher temperature leads t higher entropy.
This reaction highlights a drop in temperature which means a negative change in entropy.
methyl alcohol condenses
Condensation is the change in state from gas to liquid. Liquid particles are more ordered than gas particles so this is a negative change in entropy.
Our weight on the moon is less than it would be on earth due to a different of the strength of gravity on the moon
Answer:
Two different changes have occurred in the beaker. The description of the step 1 suggests that most likely a <u>chemical change</u> has occured while the description of the step 2 correspond to a<u> physical change</u>.
Explanation:
When the mixture of two liquid colorless substances results in the appearance of solid particles you first thing in the appareance of a new substance. If this is the case, it means that the original substances reacted chemically to form a new product, so this is a chemical change.
On the other hand, the second step describes just a physical change as it has been just that the yellow particles settled and then a physical separation by <em>decantation</em>. Decantation does not change the chemical properties of the particles settled, they are jsut separeated from the liquid. During this step both the yellow particles and the liquid in the beaker keep their chemical properties, so this is just a physical change.
Answer:
a. 102.6g/mol
b. Rb⁺
Explanation:
a. The unknown base, XOH, <em>Where X is the alkali metal</em>, reacts with HCl thus:
XOH + HCl → H₂O + XCl
<em>Where 1 mole of the hydroxide reacts per mole of acid. </em>
Moles of HCl spent to reach the equivalence point are:
17.0mL = 0.017L ₓ (2.50mol / L) = 0.0425moles of HCl
As 1 mole of HCl reacts with 1 mole of base, moles of base are 0.0425 moles.
Molar mass of a compound is the ratio between mass in grams and moles of substance, that is:
4.36g / 0.0425mol =
<h3>102.6g/mol</h3>
b) Molar mass of OH is 17g/mol, thus, the molar mass of the alkali metal is:
102.6g/mol - 17g/mol = 85.6g/mol
The mass of Rb is 85.5g/mol, thus, the identity of the alkali metal is
<h3>Rb⁺</h3>
