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3 years ago

Fluorin is often added to drinking water and toothpaste

Chemistry

2 answers:

Svetradugi [14.3K]3 years ago

4 0

This is true i think if that is a question

liq [111]3 years ago

4 0

This false. The correct answer is fluoride.

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76/304=81/k what is K and show work plez

siniylev [52]

You can cross multiply and then get k alone so it would look like this:
76 81
----- = ------ = 76k= 24624
304 k ----- ----------- = k = 324
76 76

so k is equal to 324

hope this helps have a nice day

4 0

3 years ago

At high temperatures phosphine (PH_3) dissociates into phosphorus and hydrogen by the following reaction: 4PH3 rightarrow P_4 +

Alex_Xolod [135]

Answer:a)p4=0.75mol

H2=4.5mol

B)PH3=1×10^7mole

P4=0.25×10^7mole

H2=1.5×10^7mole

Time taken for 3mol of phosphine to react is 54 ×10^7s

Explanation:From the balanced chemical equation

4PH3____P4+6H2

From Gay lussac law ,when gases combines

,They do so in a ratio which bear a simple ratio with their products,if gases.

So it means from the equation above

4 mol of PH3 will form 1mol of P4 and 6 mol of H2

Meaning that if 4mol of PH3 gives 1mol of P4

Then 3mol of PH3 will give 1/4 mol or 0.75 mol of P4 .

In the same vein,3mol of PH3 will give 6×3/4 mol of H2= 4.5 Mol of H2

B) molar concentration =mole/volume

Meaning mole=molar concentration ×volume

Molar concentration is given as 5Km/m^3=5000mol/m^3

Volume=2L =2×1000=2000m^3

Nos of moles=5000×2000=10^7moles

So for P4,nos of moles =1/4×10^7=0.25×10^7

ForH2 ,6/4 ×10^7=1.5×10^7 moles

Rate= volume/time

Time taken for reaction will be volume/rate=2000/3.715×10^6

=54×10^7s

5 0

3 years ago

How much heat is evolved in converting 1.00 mol of steam at 135.0 ∘c to ice at -45.0 ∘c? the heat capacity of steam is 2.01 j/(g

Viktor [21]

1 mole of steam (H2O) = 18g
Heat evolved = MCФ where m is the mass and c s specific heat capacity while Ф is change in temperature. Latent heat of fusion is 334 kj/kg while latent heat of vaporization is 2260 kj/kg and specific heat of water is 4.2 j/g/c
= 18 ×2.01 × (135-100) = 1266.3 J
0.018 × 334000 = 6012 J (change of state from gas (steam) to liquid (water)
18 × 4.186× (100 -0) = 7534.8 J
0.018 × 2260000 = 40680 J (change of state from liquid to solid ice)
18 × 2.09 × (0--45) = 1692.9 J
The total heat evolved is therefore 57186 J or 57.186 kJ

4 0

3 years ago

Question 6 *

ycow [4]

Answer:

33 g

Explanation:

Given data:

Number of moles = 5 mol

Mass of compound = 165 g

Molar mass or gram formula mass = ?

Solution:

Formula:

Number of moles = mass/ molar mass

Now we will put the values in formula.

5 mol = 165 g/ gram formula mass

Gram formula mass = 165 g / 5 mol

Gram formula mass = 33 g/mol

7 0

3 years ago

Balance the following equation __N2+__O2→__N2O

fenix001 [56]

Answer:

2N₂ + O₂ → 2N₂O

Explanation:

Given equation:

N₂ + O₂ → N₂O

In balancing a chemical equation, the number of atoms on both sides of the expression must be the same.

To solve this problem, we use a simple mathematical approach;

put coefficients a,b and c

aN₂ + bO₂ → cN₂O

Conserving N;

2a = 2c

Conserving O:

2b = c

Let a = 1, c = 1 , b = $\frac{1}{2}$

multiply through by 4

a = 2, b = 1 and c = 2

Balanced equation is;

2N₂ + O₂ → 2N₂O

3 0

3 years ago