B that’s is not a chemical change because I took the test
The mass numbers for two isotopes are unequal because they have different numbers of NEUTRONS.
True Balance forces can not change the motion or direction of an object.
Answer:
Mass = 8 g
Explanation:
Given data:
Mass of MgO formed = 20 g
Mass of oxygen needed = ?
Solution:
Chemical equation:
2Mg + O₂ → 2MgO
Number of moles of MgO:
Number of moles = mass/molar mass
Number of moles = 20 g/ 40 g/mol
Number of moles = 0.5 mol
Now we will compare the moles of MgO and O₂ from balance chemical equation:
MgO : O₂
2 : 1
0.5 : 1/2×0.5 = 0.25 mol
Mass of oxygen required:
Mass = number of moles × molar mass
Molar mass of O₂ is 32 g/mol
Mass = 0.25 mol × 32 g/mol
Mass = 8 g
Answer:
A buffer solution is prepared by adding 13.74 g of sodium acetate (NaC2H3O2) and 15.36 g of acetic acid to enough water to make 500 mL of solution.
Calculate the pH of this buffer.
Explanation:
The pH of a buffer solution can be calculated by using the Henderson-Hesselbalch equation:
![pH=pKa+log\frac{[salt]}{[acid]}](https://tex.z-dn.net/?f=pH%3DpKa%2Blog%5Cfrac%7B%5Bsalt%5D%7D%7B%5Bacid%5D%7D)
The pH of the given buffer solution can be calculated as shown below:
