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2 years ago

I need answers to question 1,2,3

Chemistry

1 answer:

sashaice [31]2 years ago

6 0

Answer:

1. 0.125 mole

2. 42.5 g

3. 0.61 mole

Explanation:

1. Determination of the number of mole of NaOH.

Mass of NaOH = 5 g

Molar mass of NaOH = 23 + 16 + 1

= 40 g/mol

Mole of NaOH =?

Mole = mass /molar mass

Mole of NaOH = 5/40

Mole NaOH = 0.125 mole

2. Determination of the mass of NH₃.

Mole of NH₃ = 2.5 moles

Molar mass of NH₃ = 14 + (3×1)

= 14 + 3

= 17 g/mol

Mass of NH₃ =?

Mass = mole × molar mass

Mass of NH₃ = 2.5 × 17

Mass of NH₃ = 42.5 g

3. Determination of the number of mole of Ca(NO₃)₂.

Mass of Ca(NO₃)₂ = 100 g

Molar mass of Ca(NO₃)₂ = 40 + 2[14 + (3×16)]

= 40 + 2[14 + 48]

= 40 + 2[62]

= 40 + 124

= 164 g/mol

Mole of Ca(NO₃)₂ =?

Mole = mass /molar mass

Mole of Ca(NO₃)₂ = 100 / 164

Mole of Ca(NO₃)₂ = 0.61 mole

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Answer:

Answers are in the explanation

Explanation:

Precision and accuracy are both statistical concepts. Precision is about how close are the measured values to each other. Accuracy is closeness of the measured values to a specific value or reference value.

There are many ways to calculate precision and accuracy, one is stimating precision as Relative Uncertainty and accuracy as Relative Error.

Formulas are:

Relative Uncertainty: Standard desviation / Measured value.

Relative Error: Measured Value - Expected Value / Expected value

Measured value is the aveage of the values.

For student 1:

Mean = 25

Standard desviation = 1.5275

Relative Uncertainty: 1.5275 / 25

Relative Uncertainty: 0.061

Relative Error: 25 - 20 / 20

Relative Error: 0.25

For student 2:

Mean = 24.5

Standard desviation = 0.5477

Relative Uncertainty: 0.5477 / 24.5

Relative Uncertainty: 0.02

Relative Error: 24.5 - 20 / 20

Relative Error: 0.225

As the student 2 has a low Relative error and uncertainty, you can say student 2 is more accurate and precise

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3 years ago

What is the chemical formula of wood?

ad-work [718]

(99% of the total mass). 49% of carbon, 44% of oxygen, 6% of hydrogen, 0.1-0.3% of nitrogen.

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3 years ago

The bond dissociation energy to break 4 bond(s) in 1 mole of CH₄ molecules is:_____ **Any help would be greatly appreciated!**

frozen [14]

Answer:

The bond dissociation energy to break 4 bonds in 1 mol of CH is 1644 kJ

Explanation:

Since there are 4 C-H bonds in CH₄, the bond dissociation energy of 1 mol of CH₄ is 4 × bond dissociation energy of one C-H bond.

From the table one mole is C-H bond requires 411 kJ, that is 411 kJ/mol. Therefore, 4 C-H bonds would require 4 × 411 kJ = 1644 kJ

So, the bond dissociation energy to break 4 bonds in 1 mol of CH₄ is 1644 kJ

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3 years ago

3.95 g of sugar (C6H12O6) is dissolved in water to make 158 mL of solution. Find the molarity.

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Answer:

[C₆H₁₂O₆] = 0.139 M

Explanation:

Molarity si defined as a sort of concentration. It indicates the moles of solute that are contained in 1 L of solution.

We can also say, that molarity are the mmoles of solute contained in 1 mL of solution.

For this case, the solute is sugar (glucose). Let's determine M (mmol/mL)

(3.95 g . 1mol / 180g) . (1000 mmol / 1mol) / 158 mL

We determine moles, we convert them to mmoles, we divide by mL

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3 years ago

Two students are working together to build two models. Both models will represent the molecular structure of sodium bicarbonate,

vfiekz [6]

Answer:

Altogether for both models; two red jellybeans, two white jellybeans, two black jellybeans and six blue jellybeans.

Note: Since no specific color was stated for oxygen atoms, the answer assigns blue colored jellybeans to represent oxygen atoms.J

Explanation:

Sodium bicarbonate, NaHCO₃ is a compound composed of one atom of sodium, one atom of hydrogen, one atom of carbon and three atoms of oxygen.

Since red jellybeans represent sodium atoms, white jellybeans represent hydrogen atoms, black jellybeans represent carbon atoms and blue jellybeans represent oxygen atoms, each of the two students will require the following number of each jellybean for their model of sodium carbonate: One red jellybean, one white jellybean, one black jellybean and three blue jellybeans.

Altogether for both models; two red jellybeans, two white jellybeans, two black jellybeans and six blue jellybeans.

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