The correct answer is Gems are rare
First you need to find the amount of mass of Na2CO3 in one moles
(Use periodic chart)
Na= 22.99 x 2 = 45.98
C = 12.01
O = 16.00 x 4 = 64.00
Add the molar masses together to get 121.99
To find how many grams are in 4 moles, times 121.99 by 4
This gives you 487.96
But the questions asks for the answer to be in kilograms nor grams, to change into kilograms divide by 1000
This gets you the answer: 0.49 kg
Answer:

Explanation:
Hello.
In this case, since the normal boiling point of X is 117.80 °C, the boiling point elevation constant is 1.48 °C*kg*mol⁻¹, the mass of X is 100 g and the boiling point of the mixture of X and KBr boils at 119.3 °C, we can use the following formula:

Whereas the Van't Hoff factor of KBr is 2 as it dissociates into potassium cations and bromide ions; it means that we can compute the molality of the solution:

Next, given the mass of solventin kg (0.1 kg from 100 g), we compute the moles KBr:

Finally, considering the molar mass of KBr (119 g/mol) we compute the mass that was dissolved:

Best regards.
Answer:

Explanation:
Hello,
In this case, for first order reactions, we can use the following integrated rate law:
![ln(\frac{[A]}{[A]_0} )=kt](https://tex.z-dn.net/?f=ln%28%5Cfrac%7B%5BA%5D%7D%7B%5BA%5D_0%7D%20%29%3Dkt)
Thus, we compute the time as shown below:
![t=-\frac{ln(\frac{[A]}{[A]_0} )}{k}=- \frac{ln(\frac{0.220M}{0.690M} )}{0.55s^{-1}} \\\\t=-\frac{-1.14}{0.550s^{-1}}\\ \\t=2.08s](https://tex.z-dn.net/?f=t%3D-%5Cfrac%7Bln%28%5Cfrac%7B%5BA%5D%7D%7B%5BA%5D_0%7D%20%29%7D%7Bk%7D%3D-%20%5Cfrac%7Bln%28%5Cfrac%7B0.220M%7D%7B0.690M%7D%20%29%7D%7B0.55s%5E%7B-1%7D%7D%20%5C%5C%5C%5Ct%3D-%5Cfrac%7B-1.14%7D%7B0.550s%5E%7B-1%7D%7D%5C%5C%20%5C%5Ct%3D2.08s)
Best regards.
Calorimetry is the measurement of the quantity of heat in a substance. It is a method that is used to measure the energy content of food. It is also used to measure the specific heat of substances.