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Lera25 [3.4K]
2 years ago
14

What are elements made of?

Chemistry
1 answer:
sveta [45]2 years ago
5 0

Answer:

atoms

Explanation:

every different element, or pure substance is made up of only one atom.

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balloon filled with water is places in a microwave until it bursts. Name two different physical changes that occur during this r
Kisachek [45]

Answer:

dont know

Explanation:

3 0
3 years ago
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In a heat engine, 700 J of heat enters the system, and the piston does 400 J of work. What is the final internal (thermal) energ
Vitek1552 [10]

The first law of thermodynamics characterises the two types of energy transfer, as heat and as thermodynamic. The final internal (thermal) energy of the system is 1,500 J.

<h3>What is internal energy?</h3>

The energy present in a system itself for conducting reactions is called internal energy.

Given,

  • Heat entering system (Q) = 700 J
  • Work done by the piston (W) = 400
  • Initial energy (\rm U_{1})= 1200 J

According to the <u>first law of thermodynamics</u>:

\rm Q = \Delta U + W

Substituting values in the above equation:

\begin{aligned}\rm Q &= \rm U_{2} - U_{1} + W\\\\\rm U_{2}  &= \rm Q - W + U_{1}\\\\\rm U_{2}  &= 700 - 400 + 1200\\\\&= 1500 \;\rm J\end{aligned}

Therefore, option D. 1500 J is the final energy.

Learn more about internal energy here:

brainly.com/question/2602565

4 0
2 years ago
Read 2 more answers
28 ml of 0.10 m hcl is added to 60 ml of 0.10 m sr(oh)2. determine the concentration of oh− in the resulting solution.
Blababa [14]
Here is an acid-base reaction. Hydrochloric acid (HCl) reacts with strontium hydroxide [ Sr(OH)2 ]

Ions H+ and OH- neutralize each other. If the amounts are not equal, one of them will be in excess. 
Follow the steps as

1. Find moles of ions: mole= Molarity * Volume (in liter) ; n= M * V OR millimole = Molarity * Volume (in ml) ;
2. Write the equation
3. Find out excess ion
4. Use final volume (V acid + V base ) to calculate concentration of excess ion.

n HCI = 28 ml * 0.10 M = 0.28 mmol, releases 0.28 mmol H+ ions
n Sr(OH)2= 60 ml * 0.10 M= 0.60 mmol, releases 2* 0.60=1.20 mmol OH- ions
since Sr(OH)2⇒ Sr2+ + 2OH-

Neutralization reaction is OH- + H+ ---> H2O. The ratio is 1:1. That means 1 mmol hydroxide ions will neutralize 1 mmol hydrogen ions. Since OH- ions are greater in amount, they will be in excess

n(OH-) - n(H+)= 1.20 - 0.28 = 0.92 mmol OH- ions UNREACTED.

Total volume= V acid + V base= 28 ml + 60 ml = 98 ml

Molarity of OH- ions= mole / Vtotal = 0.92/98= 0.009 M

The answer is 0.009 M.


5 0
3 years ago
Read 2 more answers
Which of the following weak interactions would require the least amount of energy to disrupt? Group of answer choices
SpyIntel [72]

Answer: Option (c) is the correct answer.

Explanation:

A hydrogen bond is defined as a weak bond that is formed between an electropositive atom (generally hydrogen atom) and an electronegative atom like oxygen, nitrogen and fluorine.

An ionic bond is defined as a bond formed between a metal and a non-metal and in this bond transfer of electron takes place from metal to non-metal. And, due to the presence of opposite charges on the combining atoms there exists a strong force of attraction.

Vander waal forces are defined as the weak electric forces which tend to attract neutral molecules towards each other in gases, liquefied and solidified gases.

Vander waal forces are very weak forces.

Thus, we can conclude that Van der walas interactions are weak interactions would require the least amount of energy to disrupt.

8 0
3 years ago
Read 2 more answers
The melting point of H₂O(s) is 0 °C. Would you expect the melting point of H₂S(s) to be 85 °C, 0 °C or -85 °C.? Justify your cho
dimulka [17.4K]

Answer:

-85 °C

Explanation:

O and S are in the same group( Group 16). Since S is below O it's atomic mass is higher than O. So molar mass of H2S is higher than H2O. The strength of Vanderwaal Interactions ( London dispersion forces) increases when the molar mass increases. However, only H2O can form H bonds with each other. This is because electronegativity of O is higher than S and therefore H in H2O has a higher partial positive charge than H of H2S.

H bond dominate among these 2 types of forces so the strength of attractions between molecules is higher in H2O than H2S. Therefore more energy should be supplied for H2O to break inter

molecular forces and convert from solid to liquid state than H2S. So mpt of H2O must be higher than that of H2S.

5 0
2 years ago
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