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S_A_V [24]
3 years ago
6

How would you classify the following events?

Chemistry
1 answer:
ICE Princess25 [194]3 years ago
8 0

Answer:  Event 1 is an example of a physical change and Event 2 is an example of a chemical change.

Explanation: Physical change is one in which there is no change in chemical composition of the substance. There is only a change in phase change.

Chemical change is a change in which there is a change in chemical composition and there might or might not be a phase change.

On Boiling, the water molecules remain bonded in the same form and only covert from liquid to gaseous form, thus is a physical change.

On Rusting of iron nail, the iron changes to iron oxide by combining with oxygen, there is a rearrangement of atoms and thus is a chemical change.

Fe+O_2+H_2O\rightarrow Fe_2O_3.xH_2O

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C3H8+3O2 = 3CO2+4H2O what is the enthalpy combustion
dezoksy [38]

Answer:

\Delta H_{comb}=2043.85kJ/mol

Explanation:

Hello there!

In this case, according to the given chemical reaction, it possible for us to set up the expression for the calculation of the enthalpy change as shown below:

\Delta H_r=-\Delta H_{comb}=3\Delta _fH_{CO_2}+4\Delta _fH_{H_2O}-\Delta _fH_{C_3H_8}-3\Delta _fH_{O_2}

Thus, given the values of the enthalpies of formation on the attached file, we obtain:-\Delta H_{comb}=3(-393.5kJ/mol)+4(-241.8kJ/mol)-(-103.85kJ/mol)-3(0kJ/mol)\\\\-\Delta H_{comb}=-2043.85kJ/mol\\\\\Delta H_{comb}=2043.85kJ/mol

Best regards!

8 0
3 years ago
in the two stage cooling method what is the maximum amount of time allowed for both stages cooling food from 135 to 41 degrees F
BlackZzzverrR [31]
In the past, restaurants had four hours, straight through, to cool food to 41°F or lower. Now the FDA recommends cooling food in two stages -- from 135°F to 70°F in two hours then from 70°F to 41°F or lower in an additional four hours for a total cooling time of six hours
Explanation:
the two-stage cooling method<span> is a </span><span>Food Code </span>counselled<span> procedure for cooling food in restaurants and foodservice </span>institutions<span>. </span>within the<span> two-stage cooling </span>methodology<span>, food is</span><span> cooled from 140° F (60° C) to 70° F (21° C) </span>among 2<span> hours and to 41° F (5° C) or lower </span>among<span> four hours. Use of this cooling </span>methodology<span> ensures that food is cooled quickly and safely and has no harmful effects.</span>
3 0
3 years ago
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What is the difference between a suspension, a colloid, a solution, and an emulsion?
Len [333]

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Colloid is defined as a mixture (heterogeneous and homogeneous) in which one substance of dispersed insoluble particles get suspended throughout other substance. The particle size is 1 to 100 nm. In colloid, particles are small, thus pass through filter paper. The particles of air which is dispersed in solid stone is an example colloid.

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Solution is a homogeneous mixture with clear or transparent appearance. The particle size in solution is 10^{-7}-10^{-8}cm i.e. molecule in size. There is no effect of light occurs in the solution and solution can't filtered but can separated by the physical technique i.e. distillation.

5 0
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How many kilograms are in 6.983 moles of baking soda (NaCHO3)?
nasty-shy [4]
It should be about 0.586620881 kilograms
6 0
4 years ago
Boiling is an example of a physical property. How do the particles of gas compare to the particles as a liquid?
Stolb23 [73]
Particles of gas are more scarcely placed  as compared to that of liquid.

the intermolecular forces will be less in gaseous state and hence is less stable
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3 years ago
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