Answer:
nNaOH = 0,2 mol
Trong hỗn hợp các chất đề bài cho chỉ có phenol tác dụng với NaOH
C6H5OH + NaOH → C6H5ONa + H2O
0,2 ← 0,2 (mol)
⟹ mphenol = 0,2.94 = 18,8 gam
⟹
%mC6H5OH=18,8/28,9 x100%= 65,05%
Explanation:
Answer:
d. 117 grams
Explanation:
The mass of the table salt produced will be 117 grams.
Chemical reactions obey the law of conservation of mass. In this regard, matter is neither created nor destroyed in the course of a chemical reaction. It is expected that the mass of the reactants and products remain the same.
The reaction expression:
2Na + Cl₂ → 2NaCl
So, mass of sodium = 46g
mass of chlorine formed = 71g
Mass of NaCl = 46 + 71 = 117g
Answer:
whats the question so i can answer?
25%
Explanation:
In a half life of a radioactive isotope is 1 day,it means it loses its half mass each day
We a formula for N half life
where n is the number of days
Here the isotope is kept for 2 days
so it's left over mass will be
It's left over mass 1/4th of the original mass
Now, we need to find it's percentage by multiplying with 100
<u>So</u><u> </u><u>2</u><u>5</u><u>%</u><u> </u><u>mass</u><u> </u><u>will</u><u> </u><u>be</u><u> </u><u>left</u><u> </u><u>after</u><u> </u><u>2</u><u> </u><u>day</u><u> </u><u>of</u><u> </u><u>half</u><u> </u><u>life</u><u> </u><u>radioactive</u><u> </u><u>isotope</u><u>.</u><u> </u>
The correct answer is a. This is because the pH of a solution is defined as -log10(concentration of H+ ions). An inverse logarithmic scale such as this means that a solution with a lower concentration of H+ ions will have a higher pH than one with a higher concentration. Therefore we know that the pH of the second sample will be higher than the first.
Since the logarithmic scale has the base 10, a change by 1 on the scale is a consequence of multiplication/division of the H+ concentration by a factor of 10. As the scale is inverse, this means that a decrease of concentration by factor 1000 is equivalent to increasing the pH by (1000/10) = 3.
