Answer : The expected coordination number of NaBr is, 6.
Explanation :
Cation-anion radius ratio : It is defined as the ratio of the ionic radius of the cation to the ionic radius of the anion in a cation-anion compound.
This is represented by,
When the radius ratio is greater than 0.155, then the compound will be stable.
Now we have to determine the radius ration for NaBr.
Given:
Radius of cation, 
= 102 pm
Radius of cation, 
= 196 pm
As per question, the radius of cation-anion ratio is between 0.414-0.732. So, the coordination number of NaBr will be, 6.
The relation between radius ratio and coordination number are shown below.
Therefore, the expected coordination number of NaBr is, 6.
Answer:
Speed = frequency x wavelength 50 cm/s = Freq x 10cm
Explanation:
Your answer is right.
Important elements to consider:
- to use the balanced equation (which you did)
- divide the masses of each compound by the correspondant molar masses (which you did)
- compare the theoretical proportions with the current proportions
Theoretical: 2 mol of Na OH : 1 mol of CuSO4
Then 4 mol of NaOH need 2 mol of CUSO4.
Given that you have more than 2 mol of of CUSO4 you have plenty of it and the NaOH will consume first, being this the limiting reagent.
Mixing calcium carbonate and HCl.
Heating copper sulfate pentahydrate.
Mixing potassium iodide and lead nitrate.
Combining magnesium and hcl.
Burning the candle.
Let's look at the available options and see what are chemical changes and what are physical changes. As a side note, line breaks, capitalization, and punctuation are VERY important. I spent almost as much time attempting to actually figure out what your options were as I spent in distinguishing between what were chemical reactions and physical changes.
Crushing calcium carbonate.
* This is a mere physical change. You start with large pieces of calcium carbonate and end up with smaller pieces. So this is a bad choice.
Mixing calcium carbonate and HCl.
* This is a chemical reaction where the calcium carbonate and hydrochloric acid react with each other and produce carbon dioxide plus other compounds. So this is a good choice.
Boiling water.
* Another physical change from liquid to vapor. You can cool down the resulting vapor and end up with the original water. So this is a bad choice.
Heating copper sulfate pentahydrate.
* This is a chemical change in that you're converting CuSO4 . 5H2O(s) into CuSO4 and H2O. So this too is a good choice.
Separating iron filing and sulfur.
* You start out with iron filings and sulfur and end up with iron filings and sulfur. Things are a bit more orderly, but no chemical reactions have occurred. So this is a bad choice.
Mixing potassium iodide and lead nitrate. * You start with 2 white solids and upon mixing them, you get a yellow solid.
A chemical reaction has occurred. So this is a good choice.
Combining magnesium and hcl.
* When you combine these two items, you get hydrogen gas as a product. So you have a chemical reaction. And this is a good choice.
Burning the candle.
* Another chemical reaction. The wax combines with the oxygen in the air and produces water vapor and carbon dioxide. So this is a good choice.
Answer:
1 and 3.
Explanation:
The entropy measures the randomness of the system, as higher is it, as higher is the entropy. The randomness is associated with the movement and the arrangement of the molecules. Thus, if the molecules are moving faster and are more disorganized, the randomness is greater.
So, the entropy (S) of the phases increases by:
S solid < S liquid < S gases.
1. The substance is going from solid to gas, thus the entropy is increasing.
2. The substance is going from a disorganized way (the molecules of I are disorganized) to an organized way (the molecules join together to form I2), thus the entropy is decreasing.
3. The molecules go from an organized way (the atom are joined together) to a disorganized way, thus the entropy increases.
4. The ions are disorganized and react to form a more organized molecule, thus the entropy decreases.
