Answer:
clf3
Explanation:
it occupied more than 8 valence electrons
True: due to
<span>- A stock solution is a solution that has been prepared with a greater concentration of solute than is needed for a procedure, so it must be diluted to the proper concentration(s) before use.
- It is very important that you master the concepts and techniques of preparing dilutions .
- A dilution is made by taking a measured portion of a stock solution, and adding to it a solvent (water or a buffer).
- This creates a new solution with a lower concentration of solute than was contained in the stock solution.
- Since the solute concentration of the stock solution is known as well as the volumes of stock and solvent, it is possible to calculate the concentration of solute in the dilute solution.
- The dilute solution is always less concentrated than the stock or starting solution.
</span>So the answer is True
#1 is 6
#2 During chemistry lab, Mrs. Black’s students placed an antacid tablet in a zip lock bag. They recorded the mass of the tablet in the bag. Then they carefully added 50 grams of water and quickly sealed the bag. The tablet began to fizz and soon disappeared. The bag was filled with gas and it felt cold to the touch.
Answer:
65.8mL of water and 184.2mL of the 95% EtOH stock solution must be added.
Explanation:
To solve this question we need to find hoy many times the 95% EtOH must be diluted to obtain a 70% EtOH solution. That is:
95% / 70% = 1.357 times the solution must be diluted.
If we want to make 250mL of the diluted solution, the amount of 95% that must be added is:
250mL / 1.357 times =
184.2mL of the 95% solution must be added
And of water:
250mL - 184.2mL = 65.8mL of water
Answer:
(1) 0.035 × 10²³
Explanation:
Step 1: Calculate the mass of Fe in 100 g of Haemoglobin
Haemoglobin contains 0.33% Fe, that is, there are 0.33 g of Fe per 100 grams of Haemoglobin.
100 g Hb × 0.33 g Fe/100 g Hb = 0.33 g Fe
Step 2: Convert 0.33 g of Fe to moles
We will use the molar mass of Fe (55.85 g/mol).
0.33 g × 1 mol/55.85 g = 5.9 × 10⁻³ mol
Step 3: Convert 5.9 × 10⁻³ moles of Fe to atoms
We will use Avogadro's number.
5.9 × 10⁻³ mol × 6.02 × 10²³ atoms/1 mol = 3.5 × 10²¹ atoms (= 0.035 × 10²³)