Density is a derived unit of mass / volume.

A solution of phosphoric acid was made by dissolving 10.8 g of H3PO4 in 133.00 mL of water. The resulting volume was 137 mL. Cal

Nesterboy [21]

Answer:

Density is: 1.05 g/ml

Mole fraction solute: 0.015

Mole fraction solvent: 0.095

Molarity: 0.80 M

Molality: 0.82 m

Explanation:

A typical excersise of solution.

It is more confortable to make a table for this.

| masss | volume | mol

solute | | |

solvent | | |

solution | | |

Let's complete, what we have.

| masss | volume | mol

solute | 10.8g | |

solvent | | 133 mL |

solution | | 137 mL |

We can first, know how many moles are 10.8 g

Molar Mass H3PO4 = 97.99 g/mol

Mass / Molar mass = mol

10.8 g / 97.99 g/m = 0.110 mol

Density of water is 1 g/ml (it is a very knowly value)

From this data, we can know water mass, solvent.

Density = mass / volume

1 g/ml = mass / 133 mL

Mass = 133 g

We can also have the moles, by the molar mass of water 18 g/m

133 g / 18 g/m = 7.39 mol

| masss | volume | mol

solute | 10.8g | | 0.110 mol

solvent | 133g | 133 mL | 7.39 mol

solution | 143.8g | 137 mL | 7.50 mol

Mass of solution will be solute mass + solvent mass

Moles of solution will be solute moles + solvent moles

Now we can calculate everything.

Molarity means mol of solute in 1 L of solution. (mol/L)

We have to convert 137 mL in L (/1000)

0.137L so → 0.110 m / 0.137L = 0.80 M

Molality means mol of solute in 1kg of solvent.

We have to convert 133g in kg (/1000)

0.133 kg so → 0.110 m/0.133 kg = 0.82 m

Density is mass / volume

Solution density will be solution mass / solution volume

143.8 g/137 mL = 1.05 g/m

Molar fraction is : solute moles / total moles or solvent moles/total moles.

You can also (x 100%) to have a percent of them.

Remember sum of molar fraction = 1

Molar fraction of solute = 0.110 mol / 7.50mol = 0.015

Molar fraction of solvent = 7.39 mol / 7.50 mol = 0.985

5 0

3 years ago

One of relatively few reactions that takes place directly between two solids at room temperature is In this equation, the in Ba(

yuradex [85]

Answer:

3.14 grams of ammonium thiocyanate must be used to react completely with 6.5 g barium hydroxide octahydrate.

Explanation:

$Ba(OH)_2.8H_2O(s)+NH_4SCN(s)\rightarrow Ba(SCN)_2(s)+8H_2O(l)+NH_3(g)$

The balance chemical equation is :

$Ba(OH)_2.8H_2O(s)+2NH_4SCN(s)\rightarrow Ba(SCN)_2(s)+10H_2O(l)+2NH_3(g)$

Mass of barium hydroxide octahydrate = 6.5 g

Moles of barium hydroxide octahydrate = $\frac{6.5 g}{315 g/mol}=0.020635 mol$

According to reaction, 2 moles of ammonium thiocyanate reacts with1 mole of barium hydroxide octahydrate. The 0.020635 moles of barium hydroxide octahydrate will react with:

$\frac{2}{1}\times 0.020635 mol=0.04127 mol$

Mass of 0.04127 moles of ammonium thiocyanate;

$0.04127 mol\times 76 g/mol=3.136 g\approx 3.14 g$

3.14 grams of ammonium thiocyanate must be used to react completely with 6.5 g barium hydroxide octahydrate

3 0

4 years ago

The wavelength of a wave can be found by measuring how high the wave is measuring how many waves pass a point in a second measur

Liono4ka [1.6K]

Now that you know something about the properties of the two main types of waves (Lesson 43), we need to make sure that you can look at individual characteristics that waves can have.

Not all waves are created equal!You need to be able to see the specific “faces” that each wave can have, based on three important characteristics: frequency, wavelength, and amplitude.Frequency

When we first started looking at SHM we defined period as the amount of time it takes for one cycle to complete... seconds per cycle

Frequency is the same sort of idea, except we’re just going to flip things around.Frequency is a measurement of how many cycles can happen in a certain amount of time… cycles per second.If a motor is running so that it completes 50 revolutions in one second, I would say that it has a frequency of 50 Hertz.Hertz is the unit of frequency, and just means how many cycles per second.It is abbreviated as Hz.It is named after Heinrich Hertz, one member of the Hertz family that made many important contributions to physics.In formulas frequency appears as an "f".

Since frequency and period are exact inverses of each other, there is a very basic pair of formulas you can use to calculate one if you know the other…

It is very easy to do these calculations on calculators using the x-1 button.

Example 1: The period of a pendulum is 4.5s. Determine the frequency of this pendulum.

The period means that it will take 4.5 seconds for the pendulum to swing back and forth once. So, I expect that my frequency will be a decimal, since it will complete a fraction of a swing per second.Wavelength

Wavelength is a property of a wave that most people (once they know what to look for) can spot quickly and easily, and use it as a way of telling waves apart. Look at the following diagram...

Figure 1Any of the parts of the wave that are pointing up like mountains are called crests. Any part that is sloping down like a valley is a trough.Wavelength is defined as the distance from a particular height on the wave to the next spot on the wave where it is at the same height and going in the same direction.Usually it is measured in metres, just like any length.There isn’t a special spot you have to start on a wave to measure wavelength, just make sure you are back to the same height going in the same direction. Most people do like to measure from one crest to the next crest (or trough to trough), just because they are easy to spot.Figure 2

On a longitudinal wave, the wavelength is measured as the distance between the middles of two compressions, or the middles of two expansions.

Figure 3

This leads us to one of the most important formulas you will use when studying waves.

Frequency tells us how many waves are passing a point per second, the inverse of time.Wavelength tells us the length of those waves in metres, almost like a displacement.If we multiply these two together, we are really multiplying 1/s and m… which gives us m/s, the velocity of the wave!

v = velocity of the wave (m/s)
f = frequency (Hz)
λ = wavelength (m)

Example 2: A wave is measured to have a frequency of 60Hz. If its wavelength is 24cm, determine how fast it is moving.

Example 3: The speed of light is always 3.00e8 m/s. Determine the frequency of red light which has a wavelength of 700nm.

Be careful when changing the 700nm into metres. Some people get really caught up with changing it into regular scientific notation with only one digit before the decimal. Why bother? It's only being used in a calculation. You’ll probably just make a mistake changing the power of 10, so just substitute in the power for the prefix and leave everything else alone…700 nm = 700 x 10-9 m since “nano” is 10-9.

Amplitude

Amplitude is a measure of how big the wave is.

Imagine a wave in the ocean. It could be a little ripple or a giant tsunami.What you are actually seeing are waves with different amplitudes.They might have the exact same frequency and wavelength, but the amplitudes of the waves can be very different.

The amplitude of a wave is measured as:

the height from the equilibrium point to the highest point of a crest orthe depth from the equilibrium point to the lowest point of a troughFigure 4

When you measure the amplitude of a wave, you are really looking at the energy of the wave.

It takes more energy to make a bigger amplitude wave.Anytime you need to remember this, just think of a home stereo’s amplifier… it makes the amplitude of the waves bigger by using more electrical energy.

6 0

4 years ago

Two solutions namely, 500 ml of 0.50 m hcl and 500 ml of 0.50 m naoh at the same temperature of 21.6 are mixed in a constant-pre

weeeeeb [17]

24.6 ℃

<h3>Explanation</h3>

Hydrochloric acid and sodium hydroxide reacts by the following equation:

$\text{HCl} \; (aq) + \text{NaOH} \; (aq) \to \text{NaCl} \; (aq) + \text{H}_2\text{O} \; (aq)$

which is equivalent to

$\text{H}^{+} \; (aq) + \text{OH}^{-} \; (aq) \to \text{H}_2\text{O}\; (l)$

The question states that the second equation has an enthalpy, or "heat", of neutralization of $-56.2 \; \text{kJ}$ . Thus the combination of every mole of hydrogen ions and hydroxide ions in solution would produce $56.2 \; \text{kJ}$ or $56.2 \times 10^{3}\; \text{J}$ of energy.

500 milliliter of a 0.50 mol per liter "M" solution contains 0.25 moles of the solute. There are thus 0.25 moles of hydrogen ions and hydroxide ions in the two 0.500 milliliter solutions, respectively. They would combine to release $0.25 \times 56.2 \times 10^{3} = 1.405 \times 10^{4} \; \text{J}$ of energy.

Both the solution and the calorimeter absorb energy released in this neutralization reaction. Their temperature change is dependent on the heat capacity C of the two objects, combined.

The question has given the heat capacity of the calorimeter directly.

The heat capacity (the one without mass in the unit) of water is to be calculated from its mass and specific heat.

The calorimeter contains 1.00 liters or $1.00 \times 10^{3} \; \text{ml}$ of the 1.0 gram per milliliter solution. Accordingly, it would have a mass of $1.00 \times 10^{3} \; \text{g}$ .

The solution has a specific heat of $4.184 \; \text{J} \cdot \text{g}^{-1} \cdot \text{K}^{-1}$ . The solution thus have a heat capacity of $4.184 \times 1.00 \times 10^{3} = 4.184 \times 10^{3} \; \text{J} \cdot\text{K}^{-1}$ . Note that one degree Kelvins K is equivalent to one degree celsius ℃ in temperature change measurements.

The calorimeter-solution system thus has a heat capacity of $4.634 \times 10^{3} \; \text{J} \cdot \text{K}^{-1}$ , meaning that its temperature would rise by 1 degree celsius on the absorption of 4.634 × 10³ joules of energy. $1.405 \times 10^{4} \; \text{J}$ are available from the reaction. Thus, the temperature of the system shall have risen by 3.03 degrees celsius to 24.6 degrees celsius by the end of the reaction.

4 0

3 years ago

How many atoms are found in 4.75 moles of Fe?

aliya0001 [1]

Answer:

The answer to your question is below

Explanation:

a)

Number of atoms = ?

moles of Fe = 4.75

-Use proportions to solve this problem

1 mol of Fe --------------------- 6.023 x 10²³ atoms

4.75 moles --------------------- x

x = (4.75 x 6.023 x 10²³) / 1

x = 2.86 x 10²⁴ / 1

Number of atoms = 2.86 x 10²⁴

b)

Number of moles = ?

moles of 1.058 moles of H₂O

I think this question is incorrect, maybe you wish to know the number of atoms or grams of H₂O.

c)

Number of atoms = ?

moles of Fe = 0.759

1 mol of Fe ------------------ 6.023 x 10²³ atoms

0.759 moles --------------- x

x = (0.759 x 6.023 x 10²³) / 1

x = 4.57 x 10²³ / 1

Number of atoms of Fe = 4.57 x 10²³ atoms

d)

Number of molecules = ?

moles of H₂O = 3.5 moles

1 mol of H₂O ------------------ 6.023 x 10²³ molecules

3.5 moles ------------------ x

x = (3.5 x 6.023 x 10²³) / 1

x = 2.11 x 10²⁴ molecules

Number of molecules = 2.11 x 10²⁴

7 0

4 years ago