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miss Akunina [59]
3 years ago
9

I need help please i need to pass

Chemistry
2 answers:
max2010maxim [7]3 years ago
8 0

second one is the right answer of question number 2

goldfiish [28.3K]3 years ago
4 0
Energy was released.
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Please help on how to solve this problem it’s for isotopes
wlad13 [49]

Mg-19:

#protons = 12

#neutrons = 7

#electrons = 12

Mg-40:

#protons = 12

#neutrons = 28

#electrons = 12

8 0
2 years ago
After completing an experiment to determine gravimetrically the percentage of water in a hydrate, a student reported a value of
zzz [600]

Answer:

A. Strong initial heating caused some of the hydrate sample to spatter out of the crucible.

Explanation:

Hi

The percentage of water in the sample is lower than expected.

A. Strong initial heating caused some of the hydrate sample to spatter out of the crucible:

If part of the sample is splashed from the crucible the mass of water detected will be less.

B. The dehydrated sample absorbed moisture after heating:

If the sample absorbs water after heating the percentage of water would be higher than expected.

C. The amount of the hydrate sample used was too small:

Depending on the sample size, different procedures can be chosen for analysis.

D. The crucible was not heated to constant mass before use:

In many occasions the crucible is heated next to the sample and not in previous form.

E. Excess heating caused the dehydration sample to decompose:

If the sample decomposes during heating, the analysis should be discarded.

success with your homework

4 0
3 years ago
1. What is the colour of FeSO4.7H20 crystals?How does this colour change upon heating? Give balanced
svet-max [94.6K]
<span>1. What is the colour of FeSO4.7H20 crystals?How does this colour change upon heating?

</span><span>Melanterite or FeSO4.7H20 is green in color
</span>2FeSO4 ---> Fe2O3 + SO2 + SO3<span>

2. a. What are redox reactions?
It </span><span>is a type of chemical </span>reaction<span> that involves a transfer of electrons between two species. 
</span><span>
b.Why is the reaction between MnO2 and HCl a 
redox reaction?
Because there are atoms that are reduced and are oxidized.

c.Identify the substance oxidized and the 
substance reduced in the above reaction.

</span>MnO2<span> + 4 </span>HCl<span> ---> MnCl2 + 2H2O + Cl2
</span>Mn was reduced and Cl was oxidized
5 0
3 years ago
One mole of an ideal gas with a volume of 1.0 L and a pressure of 5.0 atm is allowed to expand isothermally into an evacuated bu
Deffense [45]

Answer:

w= - 1.7173 kJ, q= 1.7173 kJ, q(rev) = 1717.3 J = 1.7173 kJ.

Explanation:

Okay, from the question we are given the information below;

Number of moles, n= 1 mole; initial volume, v(1) = 1.0 litres (L); pressure (p) = 5atm, final volume(v2) = 2.0 Litres(L) ; the workdone, w= not given; the heat, q and q(rev)= not given and the gas was said to expand isothermally.

So, this question is a question from the part of chemistry known as thermodynamics. Therefore, grip yourself we are delving into thermodynamics 'waters' now.

For expansion isothermally; the workdone, w= -nRT ln v2/v1.

Where T= temperature= 25° C = 298 k and R= gas constant.

Therefore; workdone, w = - 1 × 8.314 × 298 × ln(2/1).

Workdone,w= - 1717.32204643. =

- 1717.3 Joules (J).

==> Workdone,w= - 1.7173 kJ.

Then, we are to find q. q can be solved by using the first law of thermodynamics, which by mathematical representation is:

∆U= q + w. Where ∆U= change in internal enegy. Since the question is dealing with isothermal expansion, there is this rule that says for an isothermal expansion ∆U = 0.

Hence, 0 =q + [- 1717.3 Joules (J)].

q=1717.3 J = 1.7173 kJ.

Finally, the q(rev) which is= nRT ln (v2/V1).

q(rev) = 1 × 8.314 × 298 ln (2/1).

q(rev) = 1717.3 J = 1.7173 kJ.

PS: please note the negative signs in the workdone and the positive sign in the q(rev).

7 0
3 years ago
How do we differentiate chemical change from physical change ​
bija089 [108]

Answer:

Chemical change :has change in mass, heat is needed, new element is formed, hard to reverse.......

Physicalchange:does not have change in mass, heat is not necessary, no new element is formed, easy to reverse

5 0
2 years ago
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