Answer:
- The option <u><em>B) Fe₂O₃ (s) + 3C(s) → 2Fe(s) + 3CO₂(g),</em></u> because the reactants are only solid units and the products contain gas molecules.
Explanation:
A <em>positive entropy change</em> means that the entropy of the products is greater than the entropy of the reactants.
Entropy in a measure of the radomness or disorder of the system.
Let's see every reaction:
<u />
<u>A) 4NO₂ (g) + 2 H₂O (l) + O₂ (g) → 4 HNO₃ (aq)</u>
Since 5 molecules of a gas (high disorder) combines with 2 molecules of liquid to produce 4 units of aqueous HNO₃ you may expect that the product is more ordered than the reactants, which means that the change in entropy is negative (the entropy decreases).
<u />
<u>B) Fe₂O₃ (s) + 3C(s) → 2Fe(s) + 3CO₂(g)</u>
The left side (reactants) show only solid substances which is a highly ordered arrangement while the right side (products) show the formation a solid (ordered arrangement) and a gas (highly disoredered arrangement), so you can predict the increase of the system entropy, i.e. a positive entropy change.
The <u>equation C)</u> shows the combination of 12 gas molecules to produce 1 solid and 6 gas molecules, so you can expect that the entropy will decrease, i.e. a negative entropy change.
For <u>equation D)</u> the products include solid and gas reactants while the product is just one unit of solid substance, letting you to predict a negative entropy change.
The answer is both are made of cells that contain a nucleus. Since they made up of cells that have a nucleus enclosed within membranes, bees and flowers can be classified under Domain Eukarya. Animals are heterotrophic, have no cell walls and no cloroplasts, while plants are autotrophic, have cell walls with cellulose and have chloroplasts.
Answer: The density of the material is 2.66 g/mL and it is likely this is made of Aluminum
Explanation:
The first step to know the material of the chunk of metal is to calculate its density. The general formula for density is P (density) = 
. Moreover, in this case, it is known the mass is 37.28 g, but the volume is not directly provided. However, we know the water in the graduated cylinder had a volume of 20.0 mL and this increased to 34.0 mL when the chunk of metal is added, this means the volume of the metal is 14 mL (34.0 mL - 20.0 mL = 14 mL). Now let's calculate the density:
This means the density of this metal is 2.66 g/mL, which can be rounded as 2. 7 g/mL, and according to the chart, this is the density of aluminum. Therefore, this material of this chunk is aluminum.
Answer:
75 ml of 0.1M base neutralizes 25 ml of 0.1M acid, which means the acid has 0.3 moles/L of H ion
but that means each molecule of the acid has 3 times as many H ions aH ions in a molecule of NaOH
which means the formula for the acid must be H3A and
the value of x in
HxA is 3
Explanation:
75ml of a solutipn of 0.1moL l-1 NaOH neutralises 25ml of a solution of an acid. The formula of the acid is HxA and the concentration of the acid is 0.1mol l-1. What is the value of x?
the concentration of both the and the base are the same at 0.1M
the base...NaOH has 0.1 moles/L of OH ion
75 ml of 0.1M base neutralizes 25 ml of 0.1M acid, which means the acid has 0.3 moles/L of H ion
but that means each molecule of the acid has 3 times as many H ions aH ions in a molecule of NaOH
which means the formula for the acid must be H3A and the value of x in
HxA is 3
Na - 1s^2, 2s^2, 2p^6, 3s^1
Ne - 1s^2, 2s^2, 2p^6
O - 1s^2, 2s^2, 2p^4
