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erastovalidia [21]
3 years ago
15

Consider melting ice cream. When it melts, it takes heat away from the environment and so the reaction is endothermic. When you

freeze ice cream, the heat is being removed from what?
Chemistry
1 answer:
ANEK [815]3 years ago
7 0
Hi!

First of all, the melting of ice cream is not a chemical reaction, because there is no change in the components of the ice cream and if you freeze the ice cream again, you will get the same ice cream that you had previously.

The melting of ice cream is an example of a physical change, in which a substance goes from solid to liquid state, and it is an endothermic physical change.

When you freeze ice cream, the heat is removed from the ice cream, making it an exothermic process, when heat is liberated to the environment and it's taken away from the substance, in this case, the ice cream.


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Determine how many grams of N2 are produced from the reaction of 8.37 g of H2O2 and 5.29 g of N2H4.
Dmitriy789 [7]
N₂H₄  +  2H₂O₂    →   N₂  +  4H₂O

mol = mass ÷ molar mass

If mass of hydrazine (N₂H₄)  = 5.29 g 
then mol of hydrazine           = 5.29 g ÷ ((14 ×2) + (1 × 4))
                                              = 0.165 mol

mole ratio of hydrazine to Nitogen is     1   :  1
  ∴ if moles of hydrazine = 0.165 mol
     then moles of nitrogen = 0.165 mol

Mass = mol × molar mass

Since mol of nitrogen (N₂)  = 0.165
then mass of hydrazine      = 0.165 × (14 × 2)
                                           = 4.62 g
5 0
3 years ago
Name an allotrope of carbon which has 60 carbon atoms
Annette [7]
Buckminster fullerene C60
5 0
3 years ago
Which substance, when dissolved in water, forms a solution that conducts an electric current?
Margarita [4]
Missing question: 
<span>(1) C2H5OH (3) C12H22O11
(2) C6H12O6 (4) CH3COOH.

Answer is: 4) CH</span>₃COOH, acetic acid.
In water, acetic acid dissociates on ions, so it can conduct electricity:
CH₃COOH(aq) ⇄ CH₃COO⁻(aq) + H⁺(aq).
When we put electrodes (cathode and anode) in acetic acid solution, positive and negative ions migrate to electrodes.<span>
Negative acetate ions go to positive electrode and gives electrons to electrode.
<span>Positive hydrogen ions go to negative electrode and gain electrons.</span></span>
6 0
3 years ago
Which Of These Is An Indication That A Chemical Reaction Has Occurred?
nikdorinn [45]

<u><em>Answer:</em></u>

Correct option is D. Formation Of A Gas

<u><em>Explanation</em></u>

The main indication of chemical is that new substances are formed which have different composition than reactant.

<u><em>Freezing of a substance: </em></u>As in this case composition remained  same, so we cant say, chemical reaction is take place, like when water freezes, it composition is same as water , so it is only its physical properties, not chemical.

<u><em>Melting of a substance:</em></u> As in this case composition remained same, so we cant say, chemical reaction is take place, like when ice melts, composition of water remained same , so it its physical properties, not chemical.

<u><em>Boiling of a substance:</em></u> As in this case composition remained same, so we cant say, chemical reaction is take place, like when water boils and become vapors, composition of water and vapors remained same , so it its physical properties, not chemical properties which show its chemical reaction.

<u><em>Formation of gas:</em></u>

In this case, chemical reaction take place. In chemical reactions, new substance are formed whose composition is different from reactants.

6 0
3 years ago
Read 2 more answers
How many moles of Ca are in 7.2x10^25 molecules of Ca<br> (show work)
Gre4nikov [31]

Answer:

<h2>119.60 moles</h2>

Explanation:

To find the number of moles in a substance given it's number of entities we use the formula

n =  \frac{N}{L} \\

where n is the number of moles

N is the number of entities

L is the Avogadro's constant which is

6.02 × 10²³ entities

From the question we have

n =  \frac{7.2 \times  {10}^{25} }{6.02 \times  {10}^{23} }   \\  =119.60132...

We have the final answer as

<h3>119.60 moles</h3>

Hope this helps you

5 0
3 years ago
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