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Zarrin [17]
3 years ago
13

An element's atomic number is 78. How many protons would an atom of this element have?

Chemistry
1 answer:
Oksanka [162]3 years ago
6 0

Answer:

78

Explanation:

atomic number is number of protons

You might be interested in
The teacher said the volume of the liquid was 500 mL when measured a student found it was 499.7 mL what is the students percent
Natalka [10]

Answer:

<h2>0.06 % </h2>

Explanation:

The percentage error of a certain measurement can be found by using the formula

P(\%) =  \frac{error}{actual \:  \: number}  \times 100\% \\

From the question

error = 500 - 499.7 = 0.3

actual volume = 500 mL

We have

p(\%) =  \frac{0.3}{500}  \times 100 \\  =  \frac{3}{50}  \\

We have the final answer as

<h3>0.06 % </h3>

Hope this helps you

4 0
3 years ago
Problem 4
Hunter-Best [27]
<h3>Answer:</h3>

1.93 g

<h3>Explanation:</h3>

<u>We are given;</u>

The chemical equation;

2C₂H₆(g) + 7O₂(g) → 4CO₂(g) + 6H₂O(l) ΔH = -3120 kJ​

We are required to calculate the mass of ethane that would produce 100 kJ of heat.

  • From the equation given;
  • 2 moles of ethane burns to produce 3120 Kilo joules of heat
  • Therefore;

Number of moles that will produce 100 kJ will be;

= (2 × 100 kJ) ÷ 3120 kJ)

= 0.0641 moles

  • But, molar mass of ethane is 30.07 g/mol

Therefore;

Mass of ethane = 0.0641 moles × 30.07 g/mol

                          = 1.927 g

                          = 1.93 g

Thus, the mass of ethane that would produce 100 kJ of heat is 1.93 g

3 0
3 years ago
A chemical reaction that has a positive δg is correctly described as
Charra [1.4K]

Answer:

Endergonic reaction or nonspontaneous reaction.

Explanation:

Gibbs free energy is a state function that determines the spontaneity or feasibility of the given reversible chemical reaction, at fixed pressure and temperature. It is given by the equation:

ΔG = ΔH - TΔS

Here, ΔG - change in Gibbs free energy

ΔH- The change in enthalpy of reaction

ΔS - The change in entropy

T- Temperature

When the <u>change in the Gibbs free energy for a given reaction is positive</u> (ΔG > 0), then that chemical reaction is known as an endergonic reaction or nonspontaneous reaction.

4 0
3 years ago
Convert 7.50 mol of Li₂O to grams
Natali5045456 [20]

Answer:

223.5 g

Explanation:

The formula between the number of moles, mass and Mr can be used to convert moles to grams.

<em>Number of moles = mass ÷ Mr</em>

So, mass = number of moles × Mr

  Mr of Li₂O = (6.9 × 2) + 16 = 29.8

∴ Mass = 7.5 × 29.8 = <u>223.5 g</u>

4 0
2 years ago
What is diffusion? How does the motion of gas molecules explain how a gas diffuses throughout a room?
Lady bird [3.3K]

Answer:

Diffusion in gases

Diffusion is driven by differences in concentration. When chemical substances such as perfume are let loose in a room, their particles mix with the particles of air. The particles of smelly gas are free to move quickly in all directions

Explanation:

hope this helps

5 0
3 years ago
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