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alina1380 [7]
2 years ago
6

Read the descriptions below of two substances and an experiment on each. Decide whether the result of the experiment tells you t

he substance is a pure substance or a mixture, if you can.
Sample A is of a coarse grey powder with a faint unpleasant smell. of the powder is put into a funnel lined with a sheet of thick paper. Distilled water is poured slowly over the powder. Most of the powder disappears, but of a gritty black sand-like material is left on the surface of the paper. Pouring more water over the black material doesn't change how much of it there is.

Sample B is a solid yellow cube with a total mass of 50.0 g. The cube is put into a beaker filled with 250. mL of water. The cube collapses into a small pile of orange powder at the bottom of the beaker. When this powder is filtered out, dried and weighed, it has a total mass of 29.9 g. If the experiment is repeated with 500. mL of water, the powder that's left over has a mass of 10.0 g.
Chemistry
1 answer:
Lelu [443]2 years ago
8 0

Answer:

Sample A - mixture

Sample B- Mixture

Explanation:

Looking at sample A, we can see that as water was poured over sample A, the sample was separated into its components as the powder disappeared leaving behind a gritty black sand-like material on the surface of the paper. A separation of the mixture has taken place.

In sample B, we can clearly see that it is a mixture because the amount of solid recovered is much less than the total mass of the solid put into the beaker. The sample must have been separated into its components.

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Determine the [OH-], pH, and pOH of a solution with a [H+] of 0.090 M at 25 °C. [OH-] = pH = pOH = 0 POH =
ValentinkaMS [17]

Answer : The concentration of OH^- ion, pH and pOH of solution is, 1.12\times 10^{-13}M, 1.05 and 12.95 respectively.

Explanation : Given,

Concentration of H^+ ion = 0.090 M

pH : It is defined as the negative logarithm of hydrogen ion or hydronium ion concentration.

The expression used for pH is:

pH=-\log [H^+]

First we have to calculate the pH.

pH=-\log [H^+]

pH=-\log (0.090)

pH=1.05

The pH of the solution is, 1.05

Now we have to calculate the pOH.

pH+pOH=14\\\\pOH=14-pH\\\\pOH=14-1.05=12.95

The pOH of the solution is, 12.95

Now we have to calculate the OH^- concentration.

pOH=-\log [OH^-]

12.95=-\log [OH^-]

[OH^-]=1.12\times 10^{-13}M

The OH^- concentration is, 1.12\times 10^{-13}M

5 0
2 years ago
Read 2 more answers
We have air (21% O2 and 79% N2) at 23 bar and 30 C. 4. What is the ideal molar volume (m^3/kmol)? a. b. What is the Z factor? Wh
k0ka [10]

Answer:

The  ideal molar volume is  \frac{V}{n}  =V_z=  0.001095 \ m^3/mol  

The  Z factor is  Z = 0.09997

The  real molar volume is \frac{V_r}{n} = V_k=   0.0001095\ \frac{m^3}{mol}

Explanation:

From the question we are told that

    The pressure is  P  = 23 \ bar =  23 *10^5 Pa

      The temperature is  T  =  30 ^ oC  = 303 \ K

According to the ideal gas equation we have that

          PV  =  nRT

=>      \frac{V}{n}=V_z= \frac{RT}{P}

Where  \frac{V}{n } is the molar volume  and  R is the gas constant with value

            R  =  8.314 \ m^3 \cdot Pa \cdot K^{-1}\cdot mol^{-1}

substituting values

            \frac{V}{n}  =V_z=  \frac{ 8.314 *  303}{23 *10^{5}}

             \frac{V}{n}  =V_z=  0.001095 \ m^3/mol            

The  compressibility factor of the gas is mathematically represented  as

            Z = \frac{P *  V_z}{RT}

substituting values        

          Z = \frac{23 *10^{5} *   0.001095}{8.314 * 303}

          Z = 0.09997

Now the real molar volume is evaluated as

         \frac{V_r}{n} = V_k=  \frac{Z *  RT }{P}

substituting values

             \frac{V_r}{n} = V_k=   \frac{0.09997 *  8.314 *  303}{23 *10^{5}}

             \frac{V_r}{n} = V_k=   0.0001095\ \frac{m^3}{mol}

8 0
3 years ago
Which is composed of alkynes?
telo118 [61]
The correct answer is letter (A) Acetylene. Acetylene is the most simplest form of alkyne and at the same time a hydrocarbon. It is unsaturated because of the presence of only two carbon atoms that are bonded together in a triple bond. I<span>n its pure, it is unstable and thus, it is usually held and handled as a solution.</span>
4 0
3 years ago
Read 2 more answers
A tank of oxygen has a volume of 1650 L. The temperature of the gas inside is 35?C. If there are 9750 moles of oxygen in the tan
Paul [167]

Answer:

2192.64 PSI.

Explanation:

  • From the general law of ideal gases:

<em>PV = nRT.</em>

where, P is the pressure of the gas in atm.

V is the volume of the container in L (V = 1650 L).

n is the no. of moles of the gas in mol (n = 9750 mol).

R is the general gas constant (R = 0.082 L.atm/mol.K).

T is the temperature of the gas in (T = 35°C + 273 = 308 K).

∴ P = nRT/V = (9750 mol)(0.082 L.atm/mol.K)(308 K)/(1650 L) = 149.2 atm.

  • <u><em>To convert from atm to PSI:</em></u>

1 atm = 14.696 PSI.

<em>∴ P = 149.2 atm x (14.696 PSI/1.0 atm) = 2192.64 PSI.</em>

4 0
3 years ago
The following are formed as white precipitates in solution except
aniked [119]

Answer:

A. Iron (III) hydroxide

Explanation:

Orange-brown or rust

6 0
2 years ago
Read 2 more answers
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