Answer:
(a) Ethyl acetate and hexane, and (c) methanol and methylene chloride.
Explanation:
re-crystallization is a technique used to purify solid compound. Ethyl acetate and hexane are good solvent pair for recrystallization because they are miscible with each other due to their good differences in polarity. ethyl acetate has polarity of 77 while hexane has 68.
water and diethyl ether are not good solvent pair for recrystallization because water and diethyl ether are immiscible. They have very far polarity values. water has 100 while diethyl ether has 35
Answer:
666,480 Joules or 669.48 kJ
Explanation:
We are given;
- Volume of water as 2.0L or 2000 ml
but, density of water is 1 g/ml
- Therefore, mass of water is 2000 g
- Initial temperature as 20 °C
- Final temperature as 99.7° C
Required to determine the heat change
We know that ;
Heat change = Mass × Temperature change × specific heat
In this case;
Specific heat of water is 4.2 J/g°C
Temperature change is 79.7 °C
Therefore;
Heat change = 2000 g × 79.7 °C × 4.2 J/g°C
= 669,480 Joules 0r 669.48 kJ
Thus, the heat change involved is 666,480 Joules or 669.48 kJ
Answer:
Explanation:
Here's where all that equation balancing is going to come into use. Since the main object of the question is not the equation, I'm just going to balance it and use it.
4Fe + 3O2 ====> 2Fe2O3
Step One
Find the number of mols of O2 in 24.9 grams of O2
1 mol O2 = 2*16 = 32 grams
x mol O2 = 24.9 grams Cross multiply
32x = 24.9 * 1 Divide by 32
x = 24.9/32
x = 0.778 moles of O2
Step Two
Type the findings under the balanced equations parts. Solve for the number of moles of Fe
4Fe + 3O2 ====> 2Fe2O3
x 0.778
Step Three
Set up the proportion
4/x = 3/0.778 Cross multiply
Step Four
Solve the proportion moles of Fe
4*0.778 = 3x
3.112 = 3x Divide by 3
3.112/3 = 3x/3
x = 1.037 moles of Fe
Step Five
Find the mass of Fe
1 mol Fe = 56 grams
1.037 mol Fe = x Cross Multiply
x = 56*1.037
x = 58.1 grams
<span>(1) The atom absorbs energy, and one or more electrons move to a higher electron shell.</span>
