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3 years ago

What does a light bulb, a toaster, a radio, and a computer all have in common???

Chemistry

2 answers:

Contact [7]3 years ago

4 0

The thing that they all have in common is that they all use electrical energy

Otrada [13]3 years ago

4 0

They all use energy........,....

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Which of the following equations are balanced?

Ber [7]

Answer:

I think the first one

Explanation:

I'm not really sure but i count it

3 0

3 years ago

On a cool, rainy day, the barometric pressure is 698 mmHg. Calculate the barometric pressure in centimeters of water (cmH2O). De

lesantik [10]

Answer:

Barometric pressure is 942.3 cm of column of water.

Explanation:

We can measure barometric pressure by measuring the height h of a column of fluid (this column of fluid exerts the same pressure as the column of air of which we are measuring pressure) using the following formula:

$P = \rho*g*h\\$

Where ρ is the density of the fluid used and g the acceleration of gravity.

Knowing that both the column of mercury (to match units, we know that 698 mmHg are the same as 69.8 cmHg) and the column of water are representing the same pressure, we can match expressions and find h for the column of water:

$\rho_{Hg} *g*h_{Hg} =\rho_{Water} *g*h_{Water}\\ \\h_{Water}=\frac{rho_{Hg} *g*h_{Hg}}{\rho_{Water} *g} = \frac{13.5g/mL *9.8m/s^{2} *69.8cm}{1g/mL *9.8m/s^{2}}=942.3 cmH_{2}O$

7 0

3 years ago

Freeze-drying is a process used to preserve food. If strawberries are to be freeze-dried, then they would be frozen to -80.00 °C

katrin2010 [14]

Answer:

1. 389 kJ; 2. 7.5 µg; 3. 6.25 days

Explanation:

1. Energy required

The water is converted directly from a solid to a gas (sublimation).

They don't give us the enthalpy of sublimation, but

$\Delta_{\text{sub}}H = \Delta_{\text{fus}}H + \Delta_{\text{vap}}H = 6.01 + 40.68 = 46.69 \text{ kJ}\cdot\text{mol}^{-1}$

The equation for the process is then

Mᵣ: 18.02

46.69 kJ + H₂O(s) ⟶ H₂O(g)

m/g: 150

(a) Moles of water

$\text{Moles} = \text{150 g} \times \dfrac{\text{1 mol}}{\text{18.02 g}} = \text{8.324 mol}$

(b) Heat removed

46.69 kJ will remove 1 mol of ice.

$\text{Heat removed} = \text{8.234 mol} \times \dfrac{\text{46.69 kJ}}{\text{1 mol}} = \textbf{389 kJ}\\\text{It takes $\large \boxed{\textbf{389 kJ}}$ to remove 150 g of ice}$

2. Mass of water vapour in the freezer

For this calculation, we can use the Ideal Gas Law — pV = nRT

(a) Moles of water

Data:

$p = 1.00 \times 10^{-3}\text{ torr } \times \dfrac{\text{1 atm}}{\text{760 torr}} = 1.316 \times 10^{-6}\text{ atm}$

V = 5 L

T = (-80 + 273.15) K = 193.15 K

Calculation:

$\begin{array}{rcl}pV & = & nRT\\1.316 \times 10^{-6}\text{ atm} \times \text{5 L} & = & n \times 0.08206 \text{ L}\cdot\text{atm}\cdot\text{K}^{-1}\text{mol}^{-1} \times \text{193.15 K }\\6.6 \times 10^{-6} & = & 15.85n\text{ mol}^{-1} \\n & = & \dfrac{6.6 \times 10^{-6}}{15.85\text{ mol}^{-1}}\\\\& = & 4.2 \times 10^{-7} \text{ mol}\\\end{array}$

(b) Mass of water

$\text{Mass} = 4.2 \times 10^{-7} \text{ mol} \times \dfrac{\text{18.02 g}}{\text{1 mol}} = 7.5 \times 10^{-6}\text{ g} = 7.5 \, \mu \text{g}\\\\\text{At any given time, there are $\large \boxed{\textbf{7.5 $\mu$g}}$ of water vapour in the freezer.}$

3. Time for removal

You must remove 150 mL of water.

It takes 1 h to remove 1 mL of water.

$\text{Time} = \text{150 mL} \times \dfrac{\text{1 h}}{\text{1 mL}} = \text{150 h} = \text{6.25 days}$

5 0

4 years ago

What is the difference between the compounds Fe2O3 and FeO? Why are they not both called simply iron oxide?

Kitty [74]

There is a big different. Iron (Fe) is a transitional metal. these type of metals are known to have different "versions" of the same element with different charges. Iron has two ions, Fe+2 and Fe+3. so the molecular formula varies depending on which iron ion you have.

Oxygen is a nonmetal and it will always have the same charge, -2.

remember that when you put two atoms together, you "cross" the charges and put them as a suffix. I have attached a picture as a visual aid of how to do this.

so, if you put together Fe+2 and oxygen you can get Fe2O2, which simplifies to FeO since the have the same suffix.this compound is called Iron (II) oxide because the iron is the one with charge +2.

so, if you put together Fe+3 and oxygen you can get Fe2O3. this compound is called Iron (III) oxide because the iron is the one with charge +3.

7 0

3 years ago

What types of elements join to form<br> molecular compounds?

shutvik [7]

A binary molecular compound is a molecular compound that is composed of two elements. In general, the elements that combine to form binary molecular compounds are both nonmetals. This contrasts with ionic compounds, which usually involve bonds between metal ions and nonmetal ions.

8 0

4 years ago

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