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3 years ago

The melting point of table salt is 801 degrees C. Is this a physical or chemical property?

1 answer:

3 0

<span>This is a physical property. Physical properties involve changes of phase, or state of matter, of which melting is an example. Melting involves a change from a solid state to a liquid state. The internal energy of the solid increases, usually by applying heat, which increases the temperature to the melting point of the substance.</span>

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If element X has 83 protons, how many electrons does it have? ______ electrons

Zolol [24]

The element has 83 electrons

5 0

3 years ago

Which of the following solutions is more concentrated?<br> 0.50M KCl or 5.0% (w/v) KCl

HACTEHA [7]

.50 M KCl because 5% is the same as .05, which makes the .50M more concentrated.

6 0

3 years ago

How many grams of dry nh4cl need to be added to 2.50 l of a 0.800 m solution of ammonia, nh3, to prepare a buffer solution that

tia_tia [17]

Answer:

The correct answer is 574.59 grams.

Explanation:

Based on the given information, the number of moles of NH₃ will be,

= 2.50 L × 0.800 mol/L

= 2 mol

The given pH of a buffer is 8.53

pH + pOH = 14.00

pOH = 14.00 - pH

pOH = 14.00 - 8.53

pOH = 5.47

The Kb of ammonia given is 1.8 * 10^-5. Now pKb = -logKb,

= -log (1.8 ×10⁻⁵)

= 5.00 - log 1.8

= 5.00 - 0.26

= 4.74

Based on Henderson equation:

pOH = pKb + log ([salt]/[base])

pOH = pKb + [NH₄⁺]/[NH₃]

5.47 = 4.74 + log ([NH₄⁺]/[NH₃])

log([NH₄⁺]/[NH₃]) = 5.47-4.74 = 0.73

[NH₄⁺]/[NH₃] = 10^0.73= 5.37

[NH₄⁺ = 5.37 × 2 mol = 10.74 mol

Now the mass of dry ammonium chloride required is,

mass of NH₄Cl = 10.74 mol × 53.5 g/mol

= 574.59 grams.

8 0

3 years ago

Hydrogen gas was collected by water displacement. what was pressure of the h2 collected if the temperature was 26°c?

Vedmedyk [2.9K]

The ideal gas law may be written as
$p= \frac{\rho R T}{M}$
where
p = pressure
ρ =density
T = temperature
M = molar mass
R = 8.314 J/(mol-K)

For the given problem,
ρ = 0.09 g/L = 0.09 kg/m³
T = 26°C = 26+273 K = 299 K
M = 1.008 g/mol = 1.008 x 10⁻³ kg/mol

Therefore
$p= \frac{(0.09 \, kg/m^{3})*(8.314 \, J/(mol-K))*(299 \, K)}{1.008 \times 10^{-3} \, kg/mol} =2.2195 \times 10^{5} \, Pa$

Note that 1 atm = 101325 Pa
Therefore
p = 2.2195 x 10⁵ Pa
= 221.95 kPa
= (2.295 x 10⁵)/101325 atm
= 2.19 atm

Answer:
2.2195 x 10⁵ Pa (or 221.95 kPa or 2.19 atm)

4 0

3 years ago

A compound is found to contain 7.523% phosphorus and 92.48% iodine by weight. what is the empirical formula for this compound?

RUDIKE [14]

The answer is PI3
Ratio of 1:3

5 0

3 years ago

Read 2 more answers