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DanielleElmas [232]
3 years ago
9

Does anyone know how to do number 15?

Chemistry
1 answer:
vovikov84 [41]3 years ago
6 0

Answer:

yes i do 980

Explanation:

i899 1/2

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Water has a density of 1.0 g/cm3. Glycerin, a liquid used in some soaps, has a density of 1.26 g/cm3. If an object sinks in wate
sdas [7]
For an object to sink in something, it's density has to be higher than the object it is in, so if it sinks in water the number has be higher than 1

And to float, and objects density has to be lower than that of the substance it is put in, so it has to be lower than 1.26

So between 1 and 1.26
5 0
3 years ago
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Read the given equation. 2Na + 2H2O ? 2NaOH + H2 During a laboratory experiment, a certain quantity of sodium metal reacted with
emmasim [6.3K]

Answer:

The number of moles of Na metal that used initially = 0.70 mol.

The quantity of Na metal used initially to produce 7.80 of H₂ gas = 16.02 g.

Explanation:

  • It is a stichiometry problem.

<em>2Na + 2H₂O → 2NaOH + H₂,</em>

  • The balanced equation shows that <em>2.0 moles of Na metal </em>react with 2.0 moles of water to produce 2.0 moles of NaOH and <em>1.0 mole of H₂</em>,
  • Firstly, we need to convert the volume of H₂ (7.80 L) produced to no. of moles (n) using the ideal gas law: <em>PV = nRT</em>,

where, P is the pressure of the gas in atm<em> (P at STP = 1.0 atm)</em>,

V is the volume of the gas in L <em>(V = 7.80 L)</em>,

n is the number of moles in mole,

R is the general gas constant<em> (R = 0.082 L.atm/mol)</em>,

T is the temperature of the gas in K <em>(T at STP = 0.0 °C + 273 = 273.0 K)</em>.

∴ The number of moles of H₂ gas (n) = PV / RT = [(1.0 atm)(7.80 L)] / [(0.082 L.atm/mol.K)(273.0 K)] = 0.35 mol.

<em>Using cross multiplication:</em>

2.0 moles of Na will produce → 1.0 mole of H₂, from the stichiometrey.

??? moles of Na will produce → 0.35 mole of H₂.

∴ The number of moles of Na metal that used initially = (2.0 mol)(0.35 mol) / (1.0 mol) = 0.70 mol.

Now, we can get the quantity of Na metal using the relation:

∴ mass = n x molar mass = (0.70 mol)(22.989 g/mol) = 16.02 g.

6 0
3 years ago
What is the pH of a sample with [OH-] = 2.5 x 10-11 M?
sveticcg [70]

Answer:

The pH of the sample is 3,4.

Explanation:

We calculate the pOH from the formula pOH = -log (OH-). We know that for all aqueous solutions: pH + pOH = 14, and from there we clear pH:

pOH= -log (OH-)=10,60

pH + pOH = 14

pH + 10,60 = 14

pH=14 -10,60

<em>pH=3,4</em>

3 0
3 years ago
Is it true or false I need help.
dsp73

Answer:

true

Explanation:

4 0
3 years ago
Which statement describes how chemical formulas, such as H2O, represent compounds
grandymaker [24]

Answer:

Which statements describe how chemical formulas, such as H2O, represent compounds? ... They show the elements that make up a compound. They show the types of atoms that make up a molecule. They show the number of each type of atom in a molecule.

5 0
3 years ago
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