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mina [271]
2 years ago
7

You have 281 kilojoules how many kilocalories is it need to know ASAP

Chemistry
1 answer:
Paul [167]2 years ago
5 0
67.116 kilocalories is the answer
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Can somebody help me, please!
zavuch27 [327]

Answer:

Rubidium-85=61.2

Rubidium-87=24.36

Atomic Mass=85.56 amu

Explanation:

To find the atomic mass, we must multiply the masses of the isotope by the percent abundance, then add.

<u>Rubidium-85 </u>

This isotope has an abundance of 72%.

Convert 72% to a decimal. Divide by 100 or move the decimal two places to the left.

  • 72/100= 0.72      or        72.0 --> 7.2 ---> 0.72

Multiply the mass of the isotope, which is 85, by the abundance as a decimal.

  • mass * decimal abundance= 85* 0.72= 61.2

Rubidium-85=61.2

<u>Rubidium-87</u>

This isotope has an abundance of 28%.

Convert 28% to a decimal. Divide by 100 or move the decimal two places to the left.

  • 28/100= 0.28       or        28.0 --> 2.8 ---> 0.28

Multiply the mass of the isotope, which is 87, by the abundance as a decimal.

  • mass * decimal abundance= 87* 0.28= 24.36

Rubidium-87=24.36

<u>Atomic Mass of Rubidium:</u>

Add the two numbers together.

  • Rb-85 (61.2) and Rb-87 (24.36)
  • 61.2+24.36=85.56 amu
4 0
3 years ago
Many elements will try to obtain ____ electrons in their outermost energy level (which is very stable) because filling it in may
VladimirAG [237]
I’m pretty sure 8 as well because elctrouns can’t hold more than that
8 0
3 years ago
Which basic property of a single water molecule accounts for all of its special features, including adhesion and cohesion, its a
svetlana [45]
The property is its polarity (or hydrogen bonds)
7 0
3 years ago
In the heating curve of an unknown substance, the line labeled C represents what change(s)?
IceJOKER [234]

Answer:

C) Temperature and Kinetic Energy.

Explanation:

Hello there!

In this case, according to the generic heating curve on the attached file, it possible to see that on the point C, whereas the line is diagonal, the temperature increases, but also the kinetic energy increases because the molecules gain energy due to the increase of the temperature. It is important to say that on flat lines, like those on B and D, the phase change takes place and just the potential energy change.

In such a way, we infer that the answer is C) Temperature and Kinetic Energy.

Best regards!

6 0
3 years ago
Read 2 more answers
Elements in the same column of the periodic table have what in common?
Kipish [7]

Answer:

Elements in same column of periodic table have same properties.

Explanation:

The elements in the same group have same number of valance electrons thus have similar properties.

Consider the elements of group two i.e alkaline earth metals. All have two valance electrons and show similar properties.

Magnesium, barium, calcium etc.

All alkaline earth metals form salt with halogens.e.g,

Mg   +   Cl₂    →    MgCl₂

Ba    +   Br₂    →     BaBr₂

Mg   +   Br₂    →     MgBr₂

Ca    +   Br₂    →     CaBr₂

They react with oxygen and form oxides of respective metal.

2Mg   +   O₂   →    2MgO

2Ba   +   O₂   →    2BaO

2Ca   +   O₂   →    2CaO

these oxides form hydroxide when react with water,

MgO  + H₂O   →  Mg(OH)₂

BaO  + H₂O   →  Ba(OH)₂

CaO  + H₂O   →  Ca(OH)₂

With nitrogen it produced nitride,

3Mg + N₂     →  Mg₃N₂

3Ba + N₂     →  Ba₃N₂

3Ca + N₂     →  Ca₃N₂

With acid like HCl,

Mg + 2HCl  →  MgCl₂ + H₂

Ba + 2HCl  →  BaCl₂ + H₂

Ca + 2HCl  →  CaCl₂ + H₂

8 0
3 years ago
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