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3 years ago

i have a question about atoms. How would i find electrons when the atomic number is the number of protons and electrons?

1 answer:

3 0

The atomic number is the same as the amount of electrons and protons. For example:
Oxygens atomic number is 8 so the proton and electron count is 8.
Hydrogens atomic number is 1 so the proton and electron count is 1.

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A155-g sample of a unknown substance was heated from 25.0°C to 40.0°C.In the process, the substance absorbed 5696 J of energy. W

Iteru [2.4K]

The answer is: (5696 J) / (155 g) / (40.0 - 25.0)°C = 2.45 J/g·°C

3 0

3 years ago

How would life be different if there were 10 hours in a day

Anna71 [15]

Answer:

If there was only 10 hours in a day, including the night time it would be complexly new environment. Say you are up for 7 hours and sleep 3, in those 7 hours you would go to work for probably 4 hours, come home and do stuff for 3 then go to bed and do it all over again.

8 0

3 years ago

What are the mole fraction and the mass percent of a solution made by dissolving 0.21 g KBr in 0.355 L water? (d = 1.00 g/mL.) m

IRISSAK [1]

Answer:

Mol fraction H2O = 0.99991

Mol fraction KBr = 0.00009

mass % KBr = 0.059 %

mass % H2O = 99.941 %

Explanation:

Step 1: Data given

Mass of KBr = 0.21 grams

Molar mass KBr = 119 g/mol

Volume of water = 355 mL

Density of water = 1.00 g/mL

Molar mass water = 18.02 g/mol

Step 2: Calculate mass water

Mass water = 355 mL * 1g /mL

Mass water = 355 grams

Step 3: Calculate moles water

Moles water = mass water / molar mass water

Moles water = 355 grams / 18.02 g/mol

Moles water = 19.7 moles

Step 4: Calculate moles KBr

Moles KBr = 0.21 grams / 119 g/mol

Moles KBr = 0.00176 moles

Step 5: Calculate total moles

Total moles = 19.7 moles + 0.00176 moles

Total moles = 19.70176 moles

Step 6: Calculate mol fraction

Mol fraction H2O = 19.7 moles / 19.70176 moles

Mol fraction H2O = 0.99991

Step 7: Calculate mol fraction KBr

Mol fraction KBr = 0.00176 / 19.70176

Mol fraction KBr = 0.00009

Step 6: Calculate mass %

mass % KBR = (0.21 grams / (0.21 + 355) grams) *100%

mass % KBr = 0.059 %

mass % H2O = (355 grams / 355.21 grams) *100%

mass % H2O = 99.941 %

8 0

3 years ago

A sample of metal has a mass of 16.5916.59 g, and a volume of 5.815.81 mL. What is the density of this metal

Oxana [17]

Answer:

=> 2.8554 g/mL

Explanation:

To determine the formula to use in solving such a problem, you have to consider what you have been given.

We have;

mass (m) = 16.59 g

Volume (v) = 5.81 mL

From our question, we are to determine the density (rho) of the rock.

The formula:

$p = \frac{m}{v}$

Substitute the values into the formula:

$p = \frac{16.59 g}{5.81 mL} \\ = 2.8554 g/mL$

= 2.8554 g/mL

Therefore, the density (rho) of the rock is 2.8554 g/mL.

5 0

2 years ago

Bond [772]

Answer:

Explanation:

The melting point of a substance is the temperature at which its melt. The state of a substance is dependent on it's melting temperature. Generally, melting point above 25 °C is a solid.

This means phenol is a solid

Duodecane has melting point below 25 °C hence it is either a liquid or gas. However its boiling point of 216 °C means it would require higher temperature to boil it. Since 25 °C is less than 216 °C it means that it would remain in the liquid state.

Methane has melting point below 25 °C hence it is either a liquid or gas. However its boiling point of -164 °C means it boils easily even at very low temperatures. Since 25 °C is greater than -164 °C it means that it would exist in the gaseous state

8 0

3 years ago