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4 years ago

What happens when a gas reaches a cold surface and it changes into a liquid

1 answer:

4 0

To change phases, a substance either gains or looses energy. If a substance gains energy, it will become more exited and the molecules will spread out. An example of this is water boiling into gas. If it looses energy, the molecules will become less exited and come closer together. For example, freezing water takes away energy from molecules, changing it from liquid to solid

When a gas reaches a gold surface, it looses much of the energy that it had, so the gas condenses from gas to liquid phase.

Hope this helped!! :D

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What environmental factor could be altered in order to increase the initial reaction rate in experiment one if the initial conce

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7 0

3 years ago

A 2.5 g sample of french fries is placed in a calorimeter with 500.0 g of water at an initial temperature of 21 °C. After combus

SIZIF [17.4K]

Q=m°CΔT
=(500g) x (1 cal/g.°C) x (48°C-21°C) = 13500 cal
13500 cal / 1000 = 13.5 kcal

"What is the caloric value (kcal/g) of the french fries?"
13.5 kcal/ 2.5 g = 5.4 kcal/g

8 0

4 years ago

3. Which of the following are examples of chemical changes? Select all that apply.

Kruka [31]

Answer:

wood burning and cookies baking

Explanation:

took the test <333

3 0

3 years ago

When heat is applied to 80 grams of CaCO3, it yields 39 grams of B. Determine the percentage of the yield.

EleoNora [17]

The question is incomplete, the complete question is:

When heat is applied to 80 grams of CaCO3, it yields 39 grams of CaO Determine the percentage of the yield.

CaCO3→CaO + CO2

Answer: The % yield of the product is 87.05 %

Explanation:

The number of moles is defined as the ratio of the mass of a substance to its molar mass.

The equation used is:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ ......(1)

We are given:

Given mass of $CaCO_3$ = 80 g

Molar mass of $CaCO_3$ = 100 g/mol

Putting values in equation 1, we get:

$\text{Moles of }CaCO_3=\frac{80g}{100g/mol}=0.8mol$

For the given chemical reaction:

$CaCO_3\rightarrow CaO+CO_2$

By stoichiometry of the reaction:

If 1 mole of $CaCO_3$ produces 1 mole of CaO

So, 0.8 moles of $CaCO_3$ will produce = $\frac{1}{1}\times 0.8=0.8mol$ of CaO

We know, molar mass of $CaO$ = 56 g/mol

Putting values in above equation, we get:

$\text{Mass of CaO}=(0.8mol\times 56g/mol)=44.8g$

The percent yield of a reaction is calculated by using an equation:

$\% \text{yield}=\frac{\text{Actual value}}{\text{Theoretical value}}\times 100$ ......(2)

Given values:

Actual value of the product = 39 g

Theoretical value of the product = 44.8 g

Plugging values in equation 2:

$\% \text{yield}=\frac{39 g}{44.8g}\times 100\\\\\% \text{yield}=87.05\%$

Hence, the % yield of the product is 87.05 %

6 0

3 years ago

Question 4 How many carbon-carbon triple bonds are present in a molecule of 4,5-diethyloctane?

ivann1987 [24]

Answer:

We will have zero bonds

Explanation:

In this case, we have to start with the structure of 4,5-diethyloctane. This name ends with the suffix "ane" therefore we have an alkane. All the alkanes are made with single bonds between carbons and single bonds between carbon and hydrogen.

The molecule will have a carbon chain of eight carbons and we will have 2 branches, one ethyl on carbon 4 and another ethyl on carbon 5. (see figure 1)

5 0

3 years ago