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3 years ago

1. Burning a candle is a chemical change. What is the primary evidence that burning the candle is a chemical reaction?

Chemistry

1 answer:

tankabanditka [31]3 years ago

8 0

<h2>Answer 1) Option B) Temperature Change</h2><h3>Explanation : </h3>

The burning of candle is the reaction where both physical and chemical changes occurs. A physical change where the melted wax is cooled and the wax is obtained again. Whereas the chemical change takes place when the wick of the candle burns using the oxygen in the air and produces heat and light. So, this change in temperature is a chemical change as the burning process cannot be reverse, from the burnt products like soot, smoke and carbon dioxide. Therefore, the temperature change is the evidence of a chemical change in the burning of candle.

<h2>Answer 2) Option B) It is a chemical change because heat energy is absorbed and the pack gets colder.</h2><h3>Explanation :</h3>

When Clara is mixing the vial contents the ice pack gets colder. On application of the ice pack on the injured area absorbs the heat from that region and becomes more colder. This happens because in the ice pack was the medium for the temperature change that was occurring. This temperature change by absorbing heat getting colder is the evidence of a chemical change.

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PLS HELP What is the mass of hydrogen atoms that is measured at 54 u?

tankabanditka [31]

The mass of hydrogen atoms that is measured at 54 u given the relationship is 89.64×10¯²⁴ g

<h3>Conversion scale </h3>

1 u = 1.66×10¯²⁴ g

<h3>How to determine the mass of hydrogen atoms </h3>

Mass of Hydrogen (u) = 54 u
Mass of Hydrogen (g) =?

1 u = 1.66×10¯²⁴ g

Therefore

54 u = 54 × 1.66×10¯²⁴ g

54 u = 89.64×10¯²⁴ g

Thus, the mass of the hydrogen atoms measured at 54 u is 89.64×10¯²⁴ g

Learn more about conversion:

brainly.com/question/2139943

#SPJ1

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2 years ago

What happens in a decomposition reaction

Paladinen [302]

Answer:

It breaks down into multiple elements

Explanation:

A decomposition reaction is a type of chemical reaction in witch a single compound breaks down into two or more elements or new compounds. These reactions often involve an energy source such as heat, light, or electricity that breaks apart the bonds of compound

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3 years ago

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It has been suggested that the surface melting of ice plays a role in enabling speed skaters to achieve peak performance. Carry

vesna_86 [32]

Explanation:

Relation between pressure, latent heat of fusion, and change in volume is as follows.

$\frac{dP}{dT} = \frac{L}{T \times \Delta V}$

Also, $\frac{L}{T} = \Delta S^{fusion}_{m}$

where, $\Delta V^{fusion}_{m}$ is the difference in specific volumes.

Hence, $\frac{dP}{dT} = \frac{\Delta S^{fusion}_{m}}{\Delta V^{fusion}_{m}}$

As, $\Delta S^{fusion}_{m} = \frac{L}{T} = \frac{6010}{273.15}$ = 22.0 J/mol K

And, $\Delta V^{fusion}_{m} = \frac{M}{d_{H_{2}O}} - \frac{M}{d_{ice}}$ ...... (1)

where, $d_{H_{2}O}$ = density of water

$d_{ice}$ = density of ice

M = molar mass of water = $18.02 \times 10^{-3} kg$

Therefore, using formula in equation (1) we will calculate the volume of fusion as follows.

$\Delta V^{fusion}_{m} = \frac{M}{d_{H_{2}O}} - \frac{M}{d_{ice}}$

= $\frac{18.02 \times 10^{-3}}{997} - \frac{18.02 \times 10^{-3}}{920}$

= $-1.51 \times 10^{-6}$

Therefore, calculate the required pressure as follows.

$\frac{dP}{dT} = \frac{22}{-1.51 \times 10^{-6}}$

= $1.45 \times 10^{7} Pa/K$

or, = 145 bar/K

Hence, for change of 1 degree pressure the decrease is 145 bar and for 4.7 degree change dP = $145 \times 4.7 bar$

= 681.5 bar

Thus, we can conclude that pressure should be increased by 681.5 bar to cause 4.7 degree change in melting point.

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3 years ago

__________ is designed to protect you from injuries to your head, face, eyes, ears, hands, feet, respiratory tract, and body. A.

Nadusha1986 [10]

_________ is designed to protect you from injuries to your head, face, eyes, ears, hands, feet, respiratory tract, and body
the answer to this question, is B personal protective equipment
hope this helps :D

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What part of the water cycle involves the leaves of plants

zvonat [6]

Answer: The answer to this question is transpiration.

Explanation: I know this answer because i looked it up in a book. The other explanation is I study about this a lot.

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3 years ago