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3 years ago

12

melting, boiling, and bending are considered physical changes, but burning is a chemical change. explain why this is so.

1 answer:

Naya [18.7K]3 years ago

8 0

<span>So, when you make something boiling or melting, its still the same substance. Water doesn't change into something else, just change its state of matter. When you burn something, one substance reacts with another. For example, when you burn carbon in oxygen, you get carbon dioxide. That's the difference.</span>

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Which of the following would be expected to have the highest viscosity? CH3CH2OH, HOCH2OH, CH3CH2CH3

zaharov [31]

Answer: Out of the given options $HOCH_{2}OH$ is expected to have the highest viscosity.

Explanation:

The resistance occurred in the flow of a liquid substance is called viscosity.

More stronger is the intermolecular forces present in a substance more will be its resistance in its flow. Hence, more will be its viscosity.

For example, $HOCH_{2}OH$ has strong intermolecular hydrogen bonding than the one's present in $CH_{3}CH_{2}OH$ and $CH_{3}CH_{2}CH_{3}$ . This is because two-OH groups are present over here.

Thus, we can conclude that out of the given options $HOCH_{2}OH$ is expected to have the highest viscosity.

5 0

2 years ago

Jesse travels 3.0 meters east and then turns and travels 4.0 meters north. What distance did Jesse travel? 1 m 5 m, northeast 7

boyakko [2]

7.0 meters because 3.0+4.0=7

3 0

3 years ago

Read 2 more answers

Calculate the number of kilojoules to warm 125 g of iron from 23.5 °C to 78.0 °C.

Pie

3024.75 Joules needed to warm iron

5 0

3 years ago

How many kJ of heat are released by the reaction of 25.0 g of Na2O2(s) in the following reaction? (M = 78.0 g/mol for Na2O2)

solong [7]

-20.16 KJ of heat are released by the reaction of 25.0 g of Na2O2.

Explanation:

Given:

mass of Na2O2 = 25 grams

atomic mass of Na2O2 = 78 gram/mole

number of mole = $\frac{mass}{atomic mass of 1 mole}$

= $\frac{25}{78}$

=0. 32 moles

The balanced equation for the reaction:

2 Na2O2(s) + 2 H2O(l) → 4 NaOH(aq) + O2(g) ∆Hο = −126 kJ

It can be seen that 126 KJ of energy is released when 2 moles of Na2O2 undergoes reaction.

similarly 0.3 moles of Na2O2 on reaction would give:

$\frac{126}{2}$ = $\frac{x}{0.32}$

x = $\frac{126 x 0.32}{2}$

= -20.16 KJ

Thus, - 20.16 KJ of energy will be released.

6 0

3 years ago

If 42 grams of carbon and 52 grams of oxygen are used, how many grams of CO2 will be produced (Hint: find the

zavuch27 [327]

Answer:

71.5g

Explanation:

The reaction equation is given as:

C + O₂ → CO₂

Mass of C = 42g

Mass of O₂ = 52g

Unknown:

Mass of CO₂ produced = ?

Solution

Now to solve this problem, we have to find limiting reactant which is the one given in short supply in this reaction.

The extent of the reaction is controlled by this reactant.

Find the number of moles of the given species;

Number of moles = $\frac{mass}{molar mass}$

Number of moles of C = $\frac{42}{12}$ = 3.5mol

Number of moles of O₂ = $\frac{52}{32}$ = 1.63mol

Now;

From the balanced reaction equation;

1 mole of C reacted with 1 mole of O₂

We see that C is in excess and O₂ is the limiting reactant.

1 mole of O₂ will produce 1 mole of CO₂

So; 1.63mole of O₂ will produce 1.63 mole of CO₂

Mass of CO₂ = number of moles x molar mass

Molar mass of CO₂ = 44g/mol

Mass of CO₂ = 1.63 x 44 = 71.5g

8 0

2 years ago