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Kruka [31]
3 years ago
9

Chemical reactions occur when molecules or atoms collide so that the bonds between atoms break and new bonds form. breaking the

bonds of the reactants requires energy; whereas, bond formation releases energy. select the statements regarding energy changes during a reaction that are true.
Chemistry
1 answer:
katen-ka-za [31]3 years ago
8 0
If two substances react and the temperature of the mixture decreases, the reaction is endothermic<span>. If two substances react and the temperature of the mixture increases, the reaction is </span>exothermic<span>. A chemical reaction involves the </span>breaking<span> of bonds in the reactants and the forming of bonds in the products.</span>
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Assume that 12.0 g of oxygen are reacted with 20.0 g of magnesium to produce magnesium oxide.
FinnZ [79.3K]
Write out the eqn of magnesium and oxygen. this should be under “metals” chapter. do revise.

next, find the mols of both oxygen and magnesium. compare the ratios and find the LIMITING REAGENT.

use the mols of the limiting reagent to compare with the mols of the product.

take the mols of the product/mr of the product.

this will give u the mass.
8 0
3 years ago
Warm air _____.
svp [43]

Answer:

cools as it rises, then sinks back down

Explanation:

The movement of air is a convection current. Convection currents occur when warm air rises, cools down, and sinks due to gained density, replacing the warm air closer to the ground, creating a cycle.

5 0
3 years ago
A gas mixture contains oxygen, nitrogen, and carbon dioxide. It has a pressure of 250 mmHg. If the pressure of oxygen is 50 mmHg
kondor19780726 [428]

Answer:

P_{CO_2}=25mmHg

Explanation:

Hello there!

In this case, according to the Dalton's law, which explains that the total pressure of a gaseous system equals the sum of the partial pressures of the gases composing, for the gaseous mixture composed by oxygen, nitrogen and carbon dioxide it would be possible to write:

P_{tot}=P_{N_2}+P_{O_2}+P_{CO_2}

Now, given the pressure of the system and those of oxygen and nitrogen, we calculate that of carbon dioxide as shown below:

P_{CO_2}=P_{tot}-P_{N_2}-P_{O_2}\\\\P_{CO_2}=250mmHg-50mmHg-175mmHg\\\\P_{CO_2}=25mmHg

Best regards!

4 0
3 years ago
What is the force exerted if a 52kg student accelerates into their desk at 5/ms2
murzikaleks [220]

Answer:

\boxed{ \bold{ \huge{ \boxed{ \sf{260 \: newton}}}}}

Explanation:

Mass ( m ) = 52 kg

Acceleration ( a ) = 5 m / s²

Force ( F ) = ?

According to Newton's second law of motion ,

\boxed{ \sf{force = mass \times acceleration}}

\longrightarrow{ \sf{force = 52  \times 5}}

\longrightarrow{ \sf{force = 260 \: newton}}

Hope I helped!

Best regards! :D

3 0
3 years ago
Read 2 more answers
To investigate the reactivity of metals a student uses four metals. Each time they added 1 g of the metal to 25 cm³ of sulfuric
Mazyrski [523]

Answer:

Volume of the sulfuric acid (25cm³), same mass of each metal (1g)

Explanation:

In an experiment, the CONTROL VARIABLE also known as constant is the variable that is kept unchanged for all groups in an experiment. This is done in order not to influence the outcome of the experiment.

In this case, students are trying to investigate the reactivity of four different metals. They added 1 g of each metal to 25cm³ of sulfuric acid and recorded the temperature change. Based on the explanation of control variable above, the VOLUME OF SULFURIC ACID (25cm³) and the MASS OF EACH METAL (1g) are the CONTROL VARIABLES because they are the same or unchanged in this experiment.

5 0
3 years ago
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