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3 years ago

Which shows zero as significant digits?check all that apply.

1 answer:

8 0

- any zeroes between 2 non-zeroes
- any zeroes after non-zeroes in a number without a decimal point are sig figs

These are NOT:

- any zeroes before non-zeroes
- any zeroes after non-zeroes in a number without a decimal point

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When iron reacts with oxygen, it forms iron oxide, or rust.

Feliz [49]

Answer:

Mass of iron oxide: 79.85 g

Explanation:

Given data:

Mass of iron = 112 g

Mass of O₂ = 24 g

Mass of iron oxide formed = ?

Solution:

4Fe + 3O₂ → 2Fe₂O₃

Number of moles of Fe:

Number of moles = mass/ molar mass

Number of moles = 112 g/ 55.85 g/mol

Number of moles = 2 mol

Number of moles of O₂:

Number of moles = mass/ molar mass

Number of moles = 24 g/ 32 g/mol

Number of moles = 0.75 mol

Now we will compare the moles of oxygen and iron with iron oxide.

Fe : Fe₂O₃

4 : 2

2 : 2/4×2 = 1

O₂ : Fe₂O₃

3 : 2

0.75 : 2/3×0.75 = 0.5

The number of moles of iron oxide formed by oxygen are less thus it will be limiting reactant.

Mass of iron oxide:

Mass = number of moles × molar mass

Mass = 0.5 mol × 159.69 g/mol

Mass = 79.85 g

3 0

3 years ago

Dmitry_Shevchenko [17]

Answer:

Atomic number

Explanation:

6 0

3 years ago

Consider the reactionI2(g) + Cl2(g)2ICl(g)Using standard thermodynamic data at 298K, calculate the entropy change for the surrou

Georgia [21]

We know,

$\Delta H_{I_2(g)}=62.438\ KJ/mol\\\\\Delta H_{Cl_2(g)}= 0.0\ KJ/mol\\\\\Delta H_{ICl(g)}=17.78\ KJ/mol$

For given reaction, $I_2(g)+Cl_2(g)\ -->\ 2ICl(g)$

$\Delta H_{rxn}=2\Delta H_{ICl(g)}-\Delta H_{I_2(g)}-\Delta H_{Cl_2(g)}\\\\\Delta H_{rxn}=2(17.78)-0-62.438\ KJ/mol\\\\\Delta H_{rxn}=-26.878\ KJ/mol$

For , 2.41 moles of $I_2$ :

$\Delta H_{rxn}=2.41\times (-26.878)\ KJ\\\\\Delta H_{rxn}=-64.78\ KJ$

We know :

$\Delta S = -\dfrac{\Delta H_{rxn}}{T}\\\\\Delta S = -\dfrac{-64.78}{298}\ KJ/K\\\\\Delta S =-0.21738 \ KJ/K\\\\\Delta S=-217.38\ J/K$

Hence, this is the required solution.

7 0

3 years ago

What does “like dissolves like” mean?

Tems11 [23]

Answer:

c solvents dissolve chemicals with the same polarity ( ex. both are polar)

Explanation:

Like dissolves like is one of the central rule that guides the solubility of one substance in another.

It fully suggests substance having the same nature as in polarity-wise will dissolve one another.
For example, water is a polar liquid, it will dissolve table salt because it i also polar.
Water cannot dissolve oil because oil is non-polar.

4 0

3 years ago

The half-life for the radioactive decay of C-14C-14 is 5730 years. You may want to reference (Pages 598 - 605) Section 14.5 whil

KIM [24]

<u>Answer:</u> The sample of Carbon-14 isotope will take 2377.9 years to decay it to 25 %

<u>Explanation:</u>

The equation used to calculate rate constant from given half life for first order kinetics:

$t_{1/2}=\frac{0.693}{k}$