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aleksklad [387]

2 years ago

10

Will has been told to check the oxygen level in a confined space, before workers are allowed to enter. Will should verify that t

he space has at least ____ % oxygen by volume.

1 answer:

loris [4]2 years ago

8 0

19.5%.

If you need a full explanation, let me know :]

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How many atoms are in 578g Na

borishaifa [10]

1.51 x 10²⁵atoms

Explanation:

Given parameters:

Mass of Na = 578g

Unknown:

Number of atoms = ?

Solution:

To find the number of atoms, we must first find the number of moles the given mass contains.

Number of moles = $\frac{mass}{molar mass}$

molar mass of Na = 23g

Number of moles = $\frac{578}{23}$ = 25.13moles

1 mole of a substance = 6.02 x 10²³atoms

25.13 mole of Na = 25.13 x 6.02 x 10²³atoms

This gives 1.51 x 10²⁵atoms of Na

Learn more:

Avogadro's constant brainly.com/question/2746374

#learnwithBrainly

5 0

3 years ago

The molar mass of I2 is 253.80 g/mol, and the molar mass of NI3 is 394.71 g/mol. How many moles of I2 will form 3.58 g of NI3?

Nat2105 [25]

To answer the problem above first we need to find the difference of molar mass of NI3 from I2, 394.71 g/mol - 253.80 g/mol = 140.91 g/mol. Knowing the molar mass of the difference of NI3 from I2, in equation mass (g) / moles (mol) = molar mass, then we substitute. 3.58g / moles = 140.91 g/mol.
moles = 3.58 / 140.91 = 0.025 moles.

6 0

3 years ago

it takes 513 kj to remove a mole of electrons from the atoms at the surface of a piece of metal. how much energy does it take to

schepotkina [342]

Answer:

The right solution is " $8.5\times 10^{-19} \ joule$ ".

Explanation:

As we know,

1 mole electron = $6.023\times 10^{23} \ no. \ of \ electrons$

Total energy = $513 \ KJ$

= $513\times 1000 \ joule$

For single electron,

The amount of energy will be:

= $\frac{513\times 1000}{(6.023\times 10^{23})}$

= $8.5\times 10^{-19} \ joule$

8 0

2 years ago

At 580 k, 6. 42% of the molecules are in the chair form. calculate the value of the equilibrium constant for the reaction as wri

Ann [662]

Equilibrium chemical reaction between chair and boat forms is:
Kc = $\frac{[Boat form]}{[Chair form]}$
Suppose the total number of molecules is x
Number of molecules of chair form is 6.42/100 x
Number of molecules of boat form is 93.58/100 x
Kc = $\frac{(0.9358x)}{(0.0642x)}$ = 14.6

5 0

2 years ago

Find the concentration of H+ ions at a pH = 11 and

Black_prince [1.1K]

Explanation:

the pH of the solution defined as negatuve logarithm of $H^+$ ion concentration.

$pH=-\log[H^+]$

1. Hydrogen ion concentration when pH of the solution is 11.

$11=-\log[H^+]$

$[H^+]=1\times 10^{-11} mol/L$ ..(1)

At pH = 11, the concentration of $H^+$ ions is $1\times 10^{-11} mol/L$ .

2. Hydrogen ion concentration when the pH of the solution is 6.

$6=-\log[H^+]'$

$[H^+]'=1\times 10^{-6} mol/L$ ..(2)

At pH = 6, the concentration of $H^+$ ions is $1\times 10^{-6} mol/L$ .

3. On dividing (1) by (2).

$\frac{[H^+]}{[H^+]'}=\frac{1\times 10^{-11} mol/L}{1\times 10^{-6} mol/L}=1\times 10^{-5}$

The ratio of hydrogen ions in solution of pH equal to 11 to the solution of pH equal to 6 is $1\times 10^{-5}$ .

4. Difference between the $H^+$ ions at both pH:

$1\times 10^{-6} mol/L-1\times 10^{-11} mol/L=9.99\time 10^{-7} mol/L$

This means that Hydrogen ions in a solution at pH = 7 has $9.99\time 10^{-7} mol/L$ ions fewer than in a solution at a pH = 6

6 0

3 years ago

Read 2 more answers