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Savatey [412]
2 years ago
13

Help me pls I will mark you as brain

Chemistry
1 answer:
stealth61 [152]2 years ago
7 0
I’m pretty sure it’s the first one
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What is the mass in grams of 0.280 mole sample of sodium hydroxide NaOH​
vivado [14]

Answer:

The mass of 0.280 mole sample of sodium hydroxide NaOH​ is 11.2 grams.

Explanation:

To know the mass in grams of 0.280 moles of sample of sodium hydroxide NaOH, you must know the molar mass of the compound, that is, the mass of one mole of a substance, which can be an element or a compound.

So you know:

  • Na: 23 g/mole
  • O: 16 g/mole
  • H: 1 g/mole

So, the molar mass of NaOH is:

NaOH= 23 g/mole + 16 g/mole+ 1 g/mole= 40 g/mole

Then the following rule of three can be applied: if in 1 mole of sodium hydroxide there are 40 grams, in 0.280 moles how much mass is there?

mass=\frac{0.28 moles*40 grams}{1 mole}

mass= 11.2 grams

<u><em>The mass of 0.280 mole sample of sodium hydroxide NaOH​ is 11.2 grams.</em></u>

4 0
3 years ago
When the ph of an aqueous solution is changed from 1 to 2, the concentration of hydronium ions in the solution is.
kiruha [24]

Answer:

decreased by a factor of 10

Explanation:

pH is defined in such a way that;

pH= −log10(H)

Where H represents the concentration of Hydronium or Hydrogen ions

Given that pH is changed from 1 to 2,

By rearranging the above formula , we get 10−pH = H

  • if pH=1,H=10−1=0.1M
  • if pH=2,H=10−2=0.01M

Therefore,  0.1/0.01 = 10 and 0.1 > 0.01

Hence, the concentration of hydronium ions in the solution is decreased by a factor of 10

7 0
2 years ago
Diagrams, tables, and graphs are used by scientists to
Afina-wow [57]

Answer:

Since most of the data scientist collect is quantitative, data tables and charts are usually used to organize the information • Graphs are created from data tables • hope that helps love!

3 0
3 years ago
Can someone please help me ANSWER this question down below?
julsineya [31]

This statement is true

4 0
3 years ago
Photosynthesis by land plants leads to the fixation each year of about 1 kg of carbon on the average for each square meter of an
Rama09 [41]

Answer:

a) mass of carbon directly above 1 ( each)  square meter of the earth is 1.65kg

b) all CO₂ will definitely be used up from the atmosphere directly above a forest in 1.65 years

Explanation:

first we calculate the moles of carbon

moles = mass/molar mass

= 1kg/12gmol⁻¹

= 1000g/12gmol⁻¹

= 83.33 mol

now using the ideal gas equation

we find the volume of co₂required based on 83.33 moles

PVco₂ = nRT

Vco₂ = nRT/P

Vco₂ = (83.22mol × 0.0821L atm k⁻¹ mol⁻¹ 298 K) / 1 atm

Vco₂ = 2083.73 L

so since CO₂ in air is 0.0390% by volume in the atmosphere, we find the the total amount of air required to obtain 1kg carbon

therefore

Vair × 0.0390/100 = 2038.73L

Vair = (2038.73L × 100) / 0.0390

Vair = 5.23 × 10⁶L

therefore 5.23 × 10⁶ L of air will be required to obtain 1kg carbon

a)

Here we calculate the mass of air over 1 square meter of surface.

Remember that atmospheric pressure is the consequence of the force exerted by all the air above the surface; 1 bar is equivalent to 1.020×10⁴kgm⁻²

NOW

mass of air = 1.020×10⁴kgm⁻² × 1m²

= 1.020×10⁴kg

= 1.020×10⁷g    [1kg = 10³g]

we now find the moles of air associated with it

moles = mass/molar mass

= 1.020 × 10⁷g / ( 20%×Mo₂ + 80%×Mn₂)

= 1.020 × 10⁷g / ( 20%×32gmol⁻¹ + 80%×28gmol⁻¹)

= 1.020 × 10⁷g / 28.8 gmol⁻¹

= 354166.67mol

so based on the question, for each mole (air), there is 0.0390% of CO₂

now to calculate the moles of CO₂ we say;

MolesCo₂ = 0.0390/100 × 354166.67mol

= 138.125 moles

Now we calculate mass of CO₂ from the above findings

Moles = mass/molar mass

mass = moles × molar mass

= 138.125 moles × 12gmol⁻¹

= 1657.5g

we covert to KG

= 1657.5g / 1000

mass = 1.65kg

therfore mass of carbon directly above 1 ( each)  square meter of the earth is 1.65kg

b)

to find the number years required to use up all the CO₂, WE SAY

Number of years = total carbon per m² of the forest / carbon used up per m² from the forest per year

Number of years = 1.65kgm⁻² / 1kg²year⁻¹

Number of years = 1.65 years

Therefore all CO₂ will definitely be used up from the atmosphere directly above a forest in 1.65 years

6 0
3 years ago
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