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Tatiana [17]
3 years ago
9

If you are given the number of molecules in an unidentified chemical compound, can you calculate the number of moles in this sam

ple?
yes, because you know that each mole contains 6.02 x 1023 molecules

yes, as long as you can also measure the mass of the sample

no, because the number of moles depends on the volume of the sample

no, because the number of moles depends on the identity of the substance
Chemistry
2 answers:
natta225 [31]3 years ago
6 0
3rd one i hope that helps

sasho [114]3 years ago
6 0

Answer:

The correct option is A

Explanation:

Avogadro's number (6.02 × 10²³) is used to calculate the actual number of ions/atoms/moles present in the molecules of a chemical compound. To do that, avogadro's number is multiplied by the number of molecules of the compound - this is because the number of atoms/ions/moles present in one mole of any substance/compound is 6.02 × 10²³. Hence, one can calculate the the number of moles in the sample because the avogadro's number and the number of molecules of the unknown sample is known.

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The mole is defined as the amount of a substance containing the same number of particles as exactly 12 g of C-12. The amu is def
Pavlova-9 [17]

Answer:

Because it wouldn't make any sense

Explanation:

First of all, I think it's important to highlight the definition of isotope.

Isotope (Wikipedia): Variants of a particular chemical element <u>which differ in neutron number</u>...

This means that two isotopes are the same element but have different net mass per atom, due to the different number of neutrons.

Therefore, it's important to make the definition on the same isotope so that the proportion is equal. If the definition would be made on different isotopes, the proportion wouldn't have any sense. Let me be clear with this example:

mass in grams of a C-12 atom = 1.9944235 × 10 ^ -23 g  --> this is the mass of a single C atom.

By definition --> 1 mol of anything = 6.02 x 10 ^ 23 particles of anything

Therefore, we know how much a single C atom weights. How many grams do you think that 6.02 x 10 ^ 23 atoms of C (i.e a mol of C) could weight??

1 single C atom ----------------------------- 1.9944235 × 10 ^ -23 g

6.02 x 10 ^ 23 atoms of C   ------------ <u>12.006 g  !!</u>

These 12 g is the same quantity than above! Therefore, 1 mol of C weights 12 g. If the definition were made with 13 g of C-13 (the other C isotope), these numbers will not be the same --> There would be a contradiction.

Regarding the second question, we need to search Ne-20 atomic mass in grams -->  3,3509177 × 10 ^ -23 g

Hence, if we follow the same rule, the amu would be 1/12 of Ne-20.

[ 3,3509177 × 10 ^ -23 g ] / 12 = 2.79 ^ -24 g

3 0
3 years ago
Which of these Group 14 elements has the most metallic properties? 1. C 2. Ge 3. Si 4. Sn
seraphim [82]
I would say that the answer is Sn.
C-is a non-metal
Ge-is a metalliod (consists both non-metal and metal)
Si -is a metalloid
Sn- is a pure metal 
5 0
3 years ago
Read 2 more answers
An average person expends about 845 kilojoules of energy per hour of walking. Suppose a person eats 2 baked potatoes with butter
ExtremeBDS [4]

Answer:

         \large\boxed{2hours}

Explanation:

You will need to use the conversion between food calories, calories and joules.

       1\text { nutritional calorie }= 1,000cal\\ \\ 1cal=4.184joule

From a nutritional table (from the internet) you can obtain the amount of nutritional calories for each type macronutrient:<em> carbohydrates, protein, and fat.</em>

Macronutrient      food calories

Carbohydrate         4 cal/g

Protein                    4 cal/g

Fat                           9 cal/g

To convert food calories to regular calories, mutiply by the conversion factor:

                1=1,000cal/\text{nutritional calorie}

Macronutrient        calories

Carbohydrate         4,000 cal/g

Protein                    4,000 cal/g

Fat                           9,000 cal/g

To convert regular calories to joules, multiply by the conversion factor:

               1=4.184 joule/1cal

Macronutrient        energy in joules

Carbohydrate         16,736 joule/g

Protein                    16,736 joule/g

Fat                           37,656 joule/g

Now you can multiply the grams of each macronutrient in one potato by its energy content:

Macronutrient        energy/gram     ×   grams  =  total energy

Carbohydrate         16,736 joule/g   ×   37 g      =  619,232 joules

Protein                    16,736 joule/g   ×   4.3 g     =  71,968.8 joules

Fat                           37,656 joule/g  ×   4 g        = 150,624 joules

Total = 619,232 joules + 71,968.8 joules + 150,624 joules = 841,820.8 joules.

Since they are <u>two potatoes</u>, multiply by 2: × 841,820.8 joules = 1,683,641.6 joules.

Divide by 1,000 to convert to kilojoules = 1,683.64 kilojoules

Divide the total energy from the two potatoes by the <em>energy that an average person expend per hour of walking (845 kilojoules of energy per hour):</em>

       1,683.64kilojoules/845kilojouesl/hour=1.99hours\approx 2hours

7 0
3 years ago
The pressure of nitrogen gas at 35°C is changed from 0.89 atm to 4.3 atm. What will be its final temperature in Kelvin?
Alja [10]

Answer: The final temperature in Kelvin is 1488

Explanation:

To calculate the final temperature of the system, we use the equation given by Gay-Lussac Law. This law states that pressure of the gas is directly proportional to the temperature of the gas at constant pressure.

Mathematically,

\frac{P_1}{T_1}=\frac{P_2}{T_2}

where,

P_1\text{ and }T_1 are the initial pressure and temperature of the gas.

P_2\text{ and }T_2 are the final pressure and temperature of the gas.

We are given:

P_1=0.89atm\\T_1=35^0C=(35+273)K=308K\\P_2=4.3atm\\T_2=?

Putting values in above equation, we get:

\frac{0.89}{308}=\frac{4.3}{T_2}\\\\T_2=1488K

Hence, the final temperature in Kelvin is 1488

8 0
3 years ago
which quantity can be calculated for a solid compound, given only the formula of the compound and the Periodic Table of elements
Kryger [21]
You can calculate the gram formula mass of this compound by adding the atomic mass of every element in this compound according to the periodic table of elements.
7 0
3 years ago
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