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2 years ago

True or False: Both molecules and compounds are pure substances.

Chemistry

2 answers:

Solnce55 [7]2 years ago

4 0

Answer:

False

Explanation:

Hope this helps!

WARRIOR [948]2 years ago

3 0

Answer:

True

Explanation:

It's because both compounds and elements are considered pure substances and a molecules is considered an element.

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Within the water cycles, where do individual water molecules reside the longest?

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Condensation and precipitation

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Cellulose could provide an abundant and cheap form of glucose for humans. Why is cellulose not a source of nutrients for humans?

mojhsa [17]

Answer:

Option (c).

Explanation:

Cellulose is one of the most important carbohydrate of the plant that provide structural framework to the plant cells. Cellulose is made of the monomer of the glucose that are linked through the beta glycosidic linkages.

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Thus, the correct answer is option (c).

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3 years ago

Coal and petroleum are useful because the both have ___ stored in them.

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It has been suggested that the surface melting of ice plays a role in enabling speed skaters to achieve peak performance. Carry

vesna_86 [32]

Explanation:

Relation between pressure, latent heat of fusion, and change in volume is as follows.

$\frac{dP}{dT} = \frac{L}{T \times \Delta V}$

Also, $\frac{L}{T} = \Delta S^{fusion}_{m}$

where, $\Delta V^{fusion}_{m}$ is the difference in specific volumes.

Hence, $\frac{dP}{dT} = \frac{\Delta S^{fusion}_{m}}{\Delta V^{fusion}_{m}}$

As, $\Delta S^{fusion}_{m} = \frac{L}{T} = \frac{6010}{273.15}$ = 22.0 J/mol K

And, $\Delta V^{fusion}_{m} = \frac{M}{d_{H_{2}O}} - \frac{M}{d_{ice}}$ ...... (1)

where, $d_{H_{2}O}$ = density of water

$d_{ice}$ = density of ice

M = molar mass of water = $18.02 \times 10^{-3} kg$

Therefore, using formula in equation (1) we will calculate the volume of fusion as follows.

$\Delta V^{fusion}_{m} = \frac{M}{d_{H_{2}O}} - \frac{M}{d_{ice}}$

= $\frac{18.02 \times 10^{-3}}{997} - \frac{18.02 \times 10^{-3}}{920}$

= $-1.51 \times 10^{-6}$

Therefore, calculate the required pressure as follows.

$\frac{dP}{dT} = \frac{22}{-1.51 \times 10^{-6}}$

= $1.45 \times 10^{7} Pa/K$

or, = 145 bar/K

Hence, for change of 1 degree pressure the decrease is 145 bar and for 4.7 degree change dP = $145 \times 4.7 bar$

= 681.5 bar

Thus, we can conclude that pressure should be increased by 681.5 bar to cause 4.7 degree change in melting point.

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2 years ago

A substance having

denpristay [2]

Explanation:

Specific heat capacity is how much is required to heat the unit of mass by one degree. Therefore, if you have a higher heat capacity it required more energy, therefore, it takes longer to heat up. whereas having a lower heat capacity it takes less time to best up as it requires less energy.

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3 years ago