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8_murik_8 [283]
3 years ago
9

An element's atomic number is 45. how many electrons would an atom of this element have?

Chemistry
1 answer:
Umnica [9.8K]3 years ago
8 0
The atomic number shows the number of protons and the number of protons is equal to the number of electrons. Therefore there are 45 electrons present.
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Consider the reaction below. If you start with 4.00 moles of C3H8 (propane) and 4.00 moles of O2 , how many moles of propane wou
fgiga [73]

Answer:

0.800 mol

Explanation:

We have the amounts of two reactants, so this is a limiting reactant problem.  

We know that we will need a balanced equation with moles of the compounds involved.  

Step 1. <em>Gather all the information</em> in one place.

            C₃H₈ + 5O₂ ⟶ 3CO₂ + 4H₂O

n/mol:  4.00    4.00

===============

Step 2. Identify the <em>limiting reactant </em>

Calculate the <em>moles of CO₂</em> we can obtain from each reactant.  

<em>From C₃H₈:</em>

The molar ratio of CO₂: C₃H₈ is 3:1

Moles of CO₂ = 4.00 × 3/1

Moles of CO₂ = 12.0 mol CO₂

<em>From O₂</em>:

The molar ratio of CO₂: O₂ is 3:5.

Moles of CO₂ = 4.00 × ⅗

Moles of CO₂ = 2.40 mol CO₂

O₂ is the limiting reactant because it gives the smaller amount of CO₂.

==============

Step 3. Calculate the <em>moles of C₃H₈ consumed</em>.

The molar ratio of C₃H₈:O₂ is 1:5.

Moles of C₃H₈ = 4.00 × ⅕

Moles of C₃H₈ = 0.800 mol C₃H₈

7 0
3 years ago
What information does a molecular formula give?
Leokris [45]

Answer:

A. The actual number of atoms in a molecule

Explanation:

Molecular formula is simply defined as a type of chemical formula that describes the type and number of atoms present in a single molecule of a compound.

Looking at the options, the correct answer is option A.

5 0
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Read 2 more answers
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galben [10]

Answer:

7

Explanation:

The mass number is neutrons plus protons

3 0
3 years ago
In a climatological sense, dryness is a function of both annual rainfall and ________.
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Answer:

In a climatological sense, dryness is a function of both annual rainfall and evaporation

8 0
2 years ago
Calculate the heat absorbed by a sample of water that has a mass of 45.00 g when the temperature increases from 21.0oC to 38.5 o
Elenna [48]

Answer:

The heat absorbed by the sample of water is 3,294.9 J

Explanation:

Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.

The sensible heat of a body is the amount of heat received or transferred by a body when it undergoes a temperature variation (Δt) without there being a change of physical state (solid, liquid or gaseous). Its mathematical expression is:

Q = c * m * ΔT

Where Q is the heat exchanged by a body of mass m, made up of a specific heat substance c and where ΔT is the temperature variation.

In this case:

  • Q=?
  • m= 45 g
  • c= 4.184 \frac{J}{g*C}
  • ΔT= Tfinal - Tinitial= 38.5 C - 21 C= 17.5 C

Replacing:

Q= 4.184 \frac{J}{g*C} * 45 g* 17.5 C

Solving:

Q=3,294.9 J

<u><em>The heat absorbed by the sample of water is 3,294.9 J</em></u>

<u><em></em></u>

8 0
3 years ago
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