All categories

3 years ago

An unknown substance undergoes a chemical change that gives off heat. What can you tell me about this substance?

Chemistry

2 answers:

marin [14]3 years ago

7 0

On a molecular level there is a lot of movement which in turn is the reason why heat is generated.

madam [21]3 years ago

3 0

Explanation:

A chemical reaction in which heat is absorbed by the reactant molecules is known as an endothermic reaction.

For example, $A + B + Heat \rightarrow AB$

On the other hand, a chemical reaction in which heat energy is released by the reactant molecules is known as an exothermic reaction.

For example, $A + B \rightarrow AB + Heat$

Thus, we can conclude that when an unknown substance undergoes a chemical change that gives off heat then it means earlier the substance has more heat energy but after the chemical change there occurs a decrease in its heat energy because some of the heat has been released by it.

You might be interested in

The density of concentrated ammonia, which is 28.0% w/w nh3, is 0.899 g/ml. what volume of this reagent should be diluted to 1.0

vlada-n [284]

Answer: 2.4 ml

Solution :

Molar mass of $NH_3$ = 17 g/mole

Given,: 28% w/w of $NH_3$ solution means 28 g of ammonia in 100 g of solution.

Mass of solution = 100 g

Now we have to calculate the volume of solution.

$Volume=\frac{Mass}{Density}=\frac{100g}{0.899g/ml}=111.2ml$

Molarity : It is defined as the number of moles of solute present in one liter of solution.

$Molarity=\frac{n\times 1000}{V_s}$

where,

n = moles of solute $NH_3=\frac{\text {given mass}}{\text {molar mass}}=\frac{28}{17}=1.65moles$

$V_s$ = volume of solution in liter = 0.11 L

Now put all the given values in the formula of molarity, we get

$Molarity=\frac{1.65moles}{0.11L}=15mole/L$

Using molarity equation:

$M_1V_1=M_2V_2$

$15\times V_1=0.036\times 1.0\times 10^{3}$

$V_1=2.4ml$

6 0

3 years ago

What volume would a sample of gas occupy in LITERS at 0.985 atmospheres and a volume of 3.65 liters if the pressure were raised

musickatia [10]

Answer:

3.18 L

Explanation:

Step 1: Given data

Initial pressure (P₁): 0.985 atm

Initial volume (V₁): 3.65 L

Final pressure (P₂): 861.0 mmHg

Final volume (V₂): ?

Step 2: Convert P₁ to mmHg

We will use the conversion factor 1 atm = 760 mmHg.

0.985 atm × 760 mmHg/1 atm = 749 mmHg

Step 3: Calculate the final volume of the gas

Assuming ideal behavior and constant temperature, we can calculate the final volume using Boyle's law.

P₁ × V₁ = P₂ × V₂

V₂ = P₁ × V₁/P₂

V₂ = 749 mmHg × 3.65 L/861.0 mmHg = 3.18 L

7 0

2 years ago

1. Lithium, water, edible salt, chalk, Carbon, Lime, Nitrogen, Potassium, Oxygen,

Kaylis [27]

Answer:

Explanation:

An atom is the smallest unit of an element that can take part in a chemical reaction. Atoms (and there corresponding symbols) mentioned in the question are

Lithium ⇒ Li

Carbon ⇒ C

Nitrogen ⇒ N

Potassium ⇒ K

Oxygen ⇒ O

Iron ⇒ Fe

Chlorine ⇒ Cl

A compound is substance that contains two or more atoms that are chemically combined and can be represented with a chemical formula. The compounds (and there corresponding formula) mentioned in the question are

Water ⇒ H₂O

Edible salt (sodium chloride) ⇒ NaCl

Chalk (calcium carbonate) ⇒ CaCO₃

Lime (calcium oxide) ⇒ CaO

Iodides (such as sodium iodide and potassium iodide) ⇒ NaI and KI respectively

8 0

2 years ago

Wat is the meaning for autotrophs

mario62 [17]

An organism that is able to form nutritional organic substances from simple inorganic substances such as carbon dioxide.

6 0

2 years ago

Read 2 more answers

PLEASE HELP ME!!!! Which energy graph represents the nonspontaneous transition of graphite into diamond?

Viefleur [7K]

Answer:

A picture .There is high reactions in progression still the energy reaction reduced to indicate complete reaction.

4 0

2 years ago