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Sonbull [250]
3 years ago
12

If a sample of nitrogen gas (N2) contains 1.2 x 10^24 atoms of nitrogen, then about how many moles of nitrogen gas are in the sa

mple?
5.0
1.0
2.5
3.0
Chemistry
1 answer:
OLga [1]3 years ago
4 0

The number of moles of nitrogen gas is  1.0 mole


<u><em>calculation</em></u>

N2 is a molecule  therefore;

1  molecule  of N₂  = 2 atoms  of N

          ? molecules= 1.2 x10 ²⁴atoms

<em>by cross  multiplication</em>

=[( 1.2  x 10²⁴ atoms x 1  molecule) / 2 atoms]  = 6 x 10²³  molecules


According to Avogadro's  law  1  mole  =6.02 x 10²³  molecules

                                                                ?  moles= 6.0 x 10²³   molecules

<em>by cross  multiplication</em>


= [(6.0x 10²³  molecules  x 1  mole) / 6.02 x10²³  molecules]  =  1.0  mole


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A piece of material with a mass of 755 g is heated to 84.5 c and added to 50 g of water at 5
lana [24]
Alright sorry you're getting the answer hours later, but i can help with this.
so you're looking for specific heat, the equation for it is <span>macaΔTa = - mbcbΔTb with object a and object b. that's mass of a times specific heat of a times final minus initial temperature of a equals -(mass of b times specific heat of b times final minus initial temperature of b)
</span>so putting in your values is, 755g * ca * (75 celsius - 84.5 celsius) = -(50g * cb * (75 celsius - 5 celsius))
well we know the specific heat of water is always 4180J/kg celsius, so put that in for cb
with a bit of simplification to the equation by doing everything on each side first you have, -7172.5 * ca = -14630000
divide both sides by -7172.5 so you can single out ca and you get, ca= 2039.74
add units for specific heat which are J/kg celsius and the specific heat of the material is 2039.74 J/kg celsius

6 0
4 years ago
What is the molecular formula of the hydrocarbon whose molar mass is 536 g/mol and contains 89.55 w/w% carbon?
leonid [27]

Given the percentage composition of HC as C → 81.82 % and H → 18.18 %

So the ratio of number if atoms of C and H in its molecule can will be:

C : H = 81.82 12 : 18.18 1 C : H = 6.82 : 18.18 = 6.82 6.82 : 18.18 6.82 = 1 : 2.66 ≈ 3 : 8

So the Empirical Formula of hydrocarbon is:

C 3 H 8

As the mass of one litre of hydrocarbon is same as that of C O 2 The molar mass of the HC will be same as that of C O 2 i.e 44 g mol

Now let Molecular formula of the HC be ( C 3 H 8 ) n

Using molar mass of C and H the molar mass of the HC from its molecular formula is:

( 3 × 12 + 8 × 1 ) n = 44 n So 44 n = 44 ⇒ n = 1

Hence the molecular formula of HC is C 3 H 8

Does that help?

7 0
3 years ago
In an ion with an unknown charge, the total mass of all the electrons was determined to be 2.19 ✕ 10−26 g, while the total mass
Ilya [14]

Answer:

\large \boxed{\text{Fe$^{{2+}}$}}

Explanation:

1. Number of electrons

\text{Number of electrons} = 2.19 \times 10^{-26}\text{ g} \times \dfrac{\text{1 electron}}{9.109 \times 10^{-28}\text{ g}} = \text{24 electrons}

2. Number of protons

\text{Number of protons} = 4.34 \times 10^{-23}\text{ g} \times \dfrac{\text{1 proton}}{1.673 \times 10^{-24}\text{ g}} = \text{26 protons}

3. Identify the ion

An atom with 26 protons is iron, Fe.

A neutral atom of iron would have 26 electrons.

The ion has only 24 electrons, so it has lost two. The ion must have a charge of +2.

\text{The symbol for the ion is $\large \boxed{\textbf{Fe$^{\mathbf{2+}}$}}$}

4 0
3 years ago
An isopropyl solution contains 70 ml of isopropyl alcohol in 1.8 L of water. What is the percent by volume of the alcohol
xenn [34]

Answer:

3.74%

Explanation:

We express a solution's volume by volume percent concentration, % v/v,

Take the ratio of the isopropyl alcohol (IPA) volume to the total volume of the solution, which is 1800 mL of water+ 70 mL of IPA,

and multiply by 100 to get the percentage:   70/(1800+70) *100 = 0.0374*100 =  3.74%

5 0
3 years ago
An element has two isotopes, A and B, with mass numbers of 32.0 and 33.0 respectively. The relative atomic mass is 32.3. The per
vlada-n [284]

Answer:

d) A - 70% B - 30%

Explanation:

If x is the abundance of A, and 1−x is the abundance of B, then:

x (32.0) + (1−x) (33.0) = 32.3

32x + 33 − 33x = 32.3

33 − x = 32.3

x = 0.7

The abundance of A is 70%, and the abundance of B is 30%.

7 0
3 years ago
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