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3 years ago

12

What is the Law of Definite Composition and how does it apply to pure substances and mixtures?

2 answers:

Lyrx [107]3 years ago

5 0

Answer:

The Law of Definite Proportions ensures that chemical compounds are always created using the same proportions, regardless of the amount of the compound which is being made

irinina [24]3 years ago

3 0

Law of Definite Composition

A given chemical compound always contains its component elements in fixed ratio.

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Two substances A and B, initially at different temperatures, are thermally isolated from their surroundings and allowed to come

Elden [556K]

Answer:

B

Explanation:

For solving this we need a heat balance

$Q_{a} = Q_{b}\\m_{a}*C_{a}*\Delta T_{a} = m_{b}*C_{b}*\Delta T_{b}$

By changing the corresponding relations, we have

$m_{a}*C_{a}*\Delta T_{a} = \frac{1}{2}m_{a}*4C_{a}*\Delta T_{b} \\\\\\$

By cancelling similar factor, we obtain

$\Delta T_{a} = 2 \Delta T_{b}\\\frac{\Delta T_{a}}{\Delta T_{b}} = 2\\$

Which means that the change of temperature in A is twice the change of B

3 0

3 years ago

In which reaction does the oxidation number of hydrogen change? In which reaction does the oxidation number of hydrogen change?

dedylja [7]

<u>Answer:</u> The correct answer is $2Na(s)+2H_2O(l)\rightarrow 2NaOH(aq.)+H_2(g)$

<u>Explanation:</u>

Oxidation number is defined as the number which is given to an atom when it looses or gains electron. When an atom looses electron, it attains a positive oxidation state. When an atom gains electron, it attains a negative oxidation state.

Oxidation state of the atoms in their elemental state is considered as 0. Hydrogen is present as gaseous state.

For the given chemical reactions:

<u>Reaction 1:</u> $2HClO_4(aq.)+CaCO_3(s)\rightarrow Ca(ClO_4)_2(aq.)+H_2O(l)+CO_2 (g)$

Oxidation state of hydrogen on reactant side: +1

Oxidation state of hydrogen on product side: +1

Thus, the oxidation state of hydrogen is not changing.

<u>Reaction 2:</u> $CaO(s)+H_2O(l)\rightarrow Ca(OH)_2(s)$

Oxidation state of hydrogen on reactant side: +1

Oxidation state of hydrogen on product side: +1

Thus, the oxidation state of hydrogen is not changing.

<u>Reaction 3:</u> $HCl(aq.)+NaOH(aq.)\rightarrow NaCl(aq.)+H_2O(l)$

Oxidation state of hydrogen on reactant side: +1

Oxidation state of hydrogen on product side: +1

Thus, the oxidation state of hydrogen is not changing.

<u>Reaction 4:</u> $2Na(s)+2H_2O(l)\rightarrow 2NaOH(aq.)+H_2(g)$

Oxidation state of hydrogen on reactant side: +1

Oxidation state of hydrogen on product side: 0

Thus, the oxidation state of hydrogen is changing.

<u>Reaction 5:</u> $SO_2(g)+H_2O(l)\rightarrow H_2SO_3(aq.)$

Oxidation state of hydrogen on reactant side: +1

Oxidation state of hydrogen on product side: +1

Thus, the oxidation state of hydrogen is not changing.

Hence, the correct answer is $2Na(s)+2H_2O(l)\rightarrow 2NaOH(aq.)+H_2(g)$

6 0

3 years ago

1. Which sample contains a total of 9.0 * 10 ^ 23 atoms ? A) 0.50 mole of HCI B) 0.75 mole of H 2 O C) 1.5 moles of Cu D) 1.5 mo

Alchen [17]

c. 1.5 moles of Cu will contain a total of 9.0 * 10 ^ 23 atoms.

Explanation:

To convert moles into atoms, the molar amount and number of atom is multiplied by Avagadro's number.

Avagadro's number is 6.022× $10^{23}$

So applying the formula in the given sample:

A) 0.5×6.022× $10^{23}$

3.01× $10^{23}$ atoms.

B) 0.75 mole of H20

O.75×6.022× $10^{23}$

= 4.5166× $10^{23}$ atoms.

C) 1.5 moles of Cu

1.5×6.022× $10^{23}$

= 9.033× $10^{23}$

D). 1.5 moles of H2

1.5 × 2 × 6.022 × $10^{23}$

= 18.066 × $10^{23}$ atoms because H2 is 2 moles of hydrogen.

Atom is the smallest entity of matter having property of the element to which it is a part.

8 0

2 years ago

The lithosphere and the asthenosphere are made up of solid,liquid,or gas?ASAP

REY [17]

Gas, hope this helps

5 0

3 years ago

BLOOD HELPS YOUR BODY TO STAY AT TEMPERATURE OF ABOUT _____C. *

Paladinen [302]

Answer:The average normal body temperature is most often said to be 98.6° F (37° C). ... One small study even suggested that in healthy older patients, body temperature ranged from 94° F to 99.6° F, with an average of 97.7° F. Several factors can lead to a lower body temperature in older people

Explanation:so the answer would be 37

7 0

3 years ago