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Vitek1552 [10]
2 years ago
8

What are three signs that a chemical change has taken place

Chemistry
1 answer:
vladimir1956 [14]2 years ago
8 0
Three signs that a chemical change has taken place is 1) color change 2) formation of gas bubbles 3) a change in temperature ( if you have ever bleached your hair the reason why it is warm to the touch is because of a chemical reaction)
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Four properties of water are listed. It reacts with halogens to form oxygen gas as one of the products. It is transparent and ta
Bezzdna [24]

Chemical property is the property of the substances that describes the ability of the substance to involve in chemical reactions. Physical property is that which does not change the chemical composition of the substances. The following properties of water that it is transparent and tasteless in its pure form and it freezes at a temperature of 0^{0}C are physical properties as they simply indicate the change in physical state without any change in chemical composition of water.

The other two properties that water reacts with halogens to form oxygen gas as one of the products and water decomposes to form hydrogen and oxygen are chemical properties as the chemical composition of water changes in the given reaction.

Therefore the correct answer is b. 1 and 4

8 0
3 years ago
You do an experiment in which you need 0.5 moles of tyrosine (C9H11NO3). How many grams must you weigh out?
Yuki888 [10]

Answer: a)  90.5g

b) 33.6 L

Explanation:-

Molar mass of tyrosine  (C_9H_{11}NO_3)= 181 g/mol

According to Avogadro's law, 1 mole of every substance weighs equal to its molar mass.

1 mole of tyrosine  (C_9H_{11}NO_3) weighs = 181 g/mol

0.5 moles of tyrosine  (C_9H_{11}NO_3) weigh =\frac{181g/mol}{1}\times 0.5moles=90.5g

b) According to Avogadro's law, 1 mole of an ideal gas occupies 22.4 Liters at Standard conditions of temperature and pressure (STP).

1 mole of gas at STP occupy = 22.4 L

1.5 moles of gas at STP occupy =\frac{22.4L}{1}\times 1.5=33.6L



5 0
2 years ago
How to balance equations
dezoksy [38]

start the balancing by writing down how many atoms there are per element. we’ll use this as an example:

C3H8 + O2 --> H2O + CO2

C = 3 C = 1

H = 8 H = 2

O = 2 O = 3

balance the carbon first, as it is easiest to do. add a coefficient to the single carbon atom on the right of the equation to balance it with the 3 carbon atoms on the left of the equation:

C3H8 + O2 --> H2O + (3)CO2

now there are 3 carbon atoms on each side. however, when you do this, you multiply the amount of oxygen atoms you had. therefore, now, there are 6 carbon atoms in 3CO2, plus that other oxygen atom in H2O. you now have 7 O atoms instead of 3.

C = 3 C = 3

H = 8 H = 2

O = 2 O = 7

now let’s move on to the hydrogen atoms.

C3H8 + O2 --> H2O + 3CO2

you have 8 hydrogen atoms on the left side, and 2 on the right. in order to balance them, you have to multiply the right side’s hydrogen atoms by 4. 4(2) = 8.

C3H8 + O2 --> (4)H2O + 3CO2

now both hydrogen and carbon atoms are balanced. same amount on both sides. however, your oxygen atoms have changed due to the multiplying (right side). you now have 10 of them.

C = 3 C = 3

H = 8 H = 8

O = 2 O = 10

now we balance the oxygen atoms. multiply the left side of the equation’s oxygen atoms by 5. 5(2) = 10

C3H8 + (5)O2 --> 4H2O + 3CO2

the chemical equation is all balanced. basically, just multiply with numbers until it equals the same amount on both sides.

C = 3 C = 3

H = 8 H = 8

O = 10 O = 10

4 0
2 years ago
Getting a vaccine is safer than taking medication or undergoing surgery. True or false I
Ahat [919]

Answer:

false...

Explanation:

5 0
2 years ago
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How can you increase the amount of energy in a wave?
patriot [66]

Explanation:

One is amplitude, which is the distance from the rest position of a wave to the top or bottom. Large amplitude waves contain more energy. The other is frequency, which is the number of waves that pass by each second. If more waves pass by, more energy is transferred each second.

5 0
3 years ago
Read 2 more answers
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