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4 years ago

An element has an atmomic number of 68. The number of protons and electron in a neutral atom of the element are?

Chemistry

1 answer:

Bess [88]4 years ago

8 0

Answer:

Explanation:

An element whose atomic number is 68 (number Z), has 68 electrons and 68 protons. According to the periodic table it corresponds to the element Erbium (Er), whose mass number (A) is 167. The number of neutrons is 167-68 = 99.

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3 years ago

Calculate the energy (in kJ) required to heat 10.1 g of liquid water from 55 oC to 100 oC and change it to steam at 100 oC. The

Maksim231197 [3]

Answer:

$\large\boxed{\large\boxed{24.6kJ}}$

Explanation:

1. Energy to heat the liquid water from 55ºC to 100ºC

$Q=m\times C\times \Delta T$

m = 10.1g

C = 4.18g/JºC

ΔT = 100ºC - 55ºC = 45ºC

$Q=10.1g\times 4.18J/g\ºC\times 45\ºC=1,899.81J$

2. Energy to change the liquid to steam at 100ºC

$L=\lambda \times n$

λ = 40.6kJ/mol

n = 10.1g / 18.015g/mol = 0.5606mol

$L=40.6kJ/mol\times 0.5604mol=22.76214kJ=22,762.14J$

3. Total energy

$1,899.81J+22,762.14J=24,661.95J\approx24,662J\approx24.6kJ$

7 0

3 years ago

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PilotLPTM [1.2K]

lanuage ? lanuage ? lanuage ?

6 0

3 years ago

Read 2 more answers

Please show work: Question below

ozzi

Answer:

b) 2.0 mol

Explanation:

Given data:

Number of moles of Ca needed = ?

Number of moles of water present = 4.0 mol

Solution:

Chemical equation:

Ca + 2H₂O → Ca(OH)₂ + H₂

now we will compare the moles of Ca and H₂O .

H₂O : Ca

2 : 1

4.0 : 1/2×4.0 = 2.0 mol

Thus, 2 moles of Ca are needed.

3 0

3 years ago

What is the volume of a solid with a mass of 17.4 g and a density of 0.934 g /cm cubed?

Anvisha [2.4K]

Answer:

18.6 g/cm^3

Explanation:

17.4g/0.934g/cm^3

(divide)

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3 years ago