Part 1: Potassium, and Rubidium.Part 2: Calcium has 20 protons and 20 electrons because the atomic number for calcium is 20 and that determines how many protons there are and in an atom, the number of protons is the same number of electrons. Calcium has about 20 neutrons. I got the number of Neutrons by subtracting the mass number(40.078) and the atomic number(20), I got 20.078. Round to the nearest whole number because you cannot have half or partial neutron. So, Calcium has 20 protons, 20 electrons, and 20 neutrons,
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Answer:
Mass of ammonia = 34 g
Explanation:
Given data:
Number of molecules of ammonia = 1.204 × 10²⁴
Mass of ammonia = ?
Solution:
First of all we will calculate the number of moles.
one mole of ammonia = 6.022 × 10²³ molecules
n = 1 mole/6.022 × 10²³ molecules × 1.204 × 10²⁴ molecules
Number of moles = 2 mol
Mass of ammonia:
Number of moles = Mass / molar mass
Mass of ammonia = number of moles × molar mass
Mass of ammonia = 2 mol × 17 g/mol
Mass of ammonia = 34 g
Maybe because the difference in weight
Answer:
A solution is made by dissolving 4.87 g of potassium nitrate in water to a final volume of 86.4 mL solution. The weight/weight % or percent by mass of the solute is :
<u>2.67%</u>
Explanation:
Note : Look at the density of potassium nitrate in water if given in the question.
<u><em>You are calculating </em></u><u><em>weight /Volume</em></u><u><em> not weight/weight % or percent by mass of the solute</em></u>
Here the <u>weight/weight % or percent by mass</u> of the solute is asked : So first convert the<u> VOLUME OF SOLUTION into MASS</u>
Density of potassium nitrate in water KNO3 = 2.11 g/mL
![density=\frac{mass}{volume}](https://tex.z-dn.net/?f=density%3D%5Cfrac%7Bmass%7D%7Bvolume%7D)
Density = 2.11 g/mL
Volume of solution = 86.4 mL
![2.11=\frac{mass}{86.4}](https://tex.z-dn.net/?f=2.11%3D%5Cfrac%7Bmass%7D%7B86.4%7D)
![mass = 2.11\times 86.4](https://tex.z-dn.net/?f=mass%20%3D%202.11%5Ctimes%2086.4)
![mass=182.3grams](https://tex.z-dn.net/?f=mass%3D182.3grams)
Mass of Solute = 4.87 g
Mass of Solution = 183.2 g
w/w% of the solute =
![= \frac{mass\ of\ solute}{mass\ of\ solution}\times 100](https://tex.z-dn.net/?f=%3D%20%5Cfrac%7Bmass%5C%20of%5C%20solute%7D%7Bmass%5C%20of%5C%20solution%7D%5Ctimes%20100)
![=\frac{4.87}{183.2}\times 100](https://tex.z-dn.net/?f=%3D%5Cfrac%7B4.87%7D%7B183.2%7D%5Ctimes%20100)
w/w%=2.67%