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3 years ago

Select the equations below that represent physical changes.

1 answer:

6 0

Physical changes- any change in the physical properties of the substance is a physical change. Generally physical properties include color, state, size , shape, odour, appearance . In any phyical change, no new substance is formed.

Chemical changes- any change in the chemical properties of the substance is a chemical change. Chemical properties changes only when something new is formed during a reaction.

∴ Part A- 2 H2O(l) → 2 H2(g) + O2(g)

In this, H2 and O2 is produced during the reaction which is different from H20. Thus, it is a chemical change.

Part B- H2O(l) → H2O(s)

In this, only the state of water changes from liquid to solid and no new product is formed. Thus, it is a physical change.

Part C-CO2(s) → CO2(g)

In this also, only the state of CO2 changes from solid to gas and no new product is formed. Thus, it is a physical change.

Part D-H2(g) → 2 H(g)

In this reaction, H2 molecule is dissociated into 2 hydrogen atom leading to formation of new products. Thus, it is a chemical change.

Finally, equations that represent physical changes are - B and C

B. H2O(l) → H2O(s)

C. CO2(s) → CO2(g)

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If 294 grams of FeS2 is allowed ti react with 176 grams of O2 according to the following equation how many grams of Fe2O3 are pr

podryga [215]

You must balance your equation correctly.
Here is your answer:

294gFeS2 x 1molFeS2/119.99 x 11mols O2/4mols FeS2--> 6.738mol O2

176gO2 x 1mol O2/32gO2 x 4mols FeS2/11mol FeS2--> 2mols FeS2
Now choose the molecule with the lowest amount (Limiting Reagent)

2molsFeS2 x 2molsFe2O3/4molsFeS2 x 159.7g
159.7g Fe2O3 grams produced.

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3 years ago

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What is the difference between soluble and insoluble

klemol [59]

Soluble means it can be dissolved

Insoluble means it can't be dissolved

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3 years ago

The formation of iodine is described by the following chemical equation:

olga nikolaevna [1]

Answer:

N2O2(g) +O2(g) ===> 2NO2(g)

Explanation:

For a nonelementary reaction, the reaction equation is described as the sum of all the steps involved. All these steps constitute the reaction mechanism. Each step in the mechanism is an elementary reaction. The rate law of the overall reaction involves the rate determining step (slowest step) in the reaction sequence.

Now look at the overall reaction 2NO(g) + O2(g) ---------> 2NO2(g)

The two steps in the mechanism are

2NO(g) --------->N2O2(g) (fast)

N2O2(g) +O2(g) -------> 2NO2(g) (slow)

Summing all the steps and cancelling out the intermediate N2O2(g), we obtain the reaction equation;

2NO(g) + O2(g) ---------> 2NO2(g)

Hence the answer.

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3 years ago

Which of the following claims may be made based on your observations? (You will recieve negative points for wrong answers.)

Ostrovityanka [42]

Answer:

D, E and F

Explanation:

About tetrachloro cobalt complexes, the following facts have been observed

Color of the tetrachloro cobalt complexes is blue.
They do not decompose on heating that means synthesis of tetra chloro is endothermic.

About hexa aqua cobalt complexes, the following facts have been observed

Color of the hexa aqua cobalt complexes is pink color.
They decompose on heating and remain stable on cooling that means process of synthesis of hexa aqua cobalt complexes is exothermic.

Based on above, the correct statements are:

The correct is chloro cobalt complex is blue and aqua cobalt

complex is pink.

The chloro complex is favored by heating.

If the chloro complex is a product, then the reaction must be endothermic.

The correct options are D, E and F.

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3 years ago

What is the % composition of Carbon in Chromium (iii) Carbonate

photoshop1234 [79]

Step 1 - Discovering the ionic formula of Chromium (III) Carbonate

Chromium (III) Carbonate is formed by the ionic bonding between Chromium (III) (Cr(3+)) and Carbonate (CO3(2-)):

$Cr^{3+}+CO^{2-}_3\rightarrow Cr_2(CO_3)_3$

Step 2 - Finding the molar mass of the substance

To find the molar mass, we need to multiply the molar mass of each element by the number of times it appears in the formula of the substance and, finally, sum it all up.

The molar masses are 12 g/mol for C; 16 g/mol for O and 52 g/mol for Cr. We have thus:

$\begin{gathered} C\rightarrow3\times12=36 \\ \\ O\rightarrow9\times16=144 \\ \\ Cr\rightarrow2\times52=104 \end{gathered}$

The molar mass will be thus:

$M=36+104+144=284\text{ g/mol}$

Step 3 - Finding the percent composition of carbon

As we saw in the previous step, the molar mass of Cr2(CO3)3 is 284 g/mol. From this molar mass, 36 g/mol come from C. We can set the following proportion:

$\begin{gathered} 284\text{ g/mol ---- 100\%} \\ 36\text{ g/mol ----- x} \\ \\ x=\frac{36\times100}{284}=\frac{3600}{284}=12.7\text{ \%} \end{gathered}$

The percent composition of Carbon is thus 12.7 %.

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1 year ago