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Aliun [14]
3 years ago
6

When substances are formed that are different from the starting substances, a physical change has occurred. True False

Chemistry
2 answers:
Sergio039 [100]3 years ago
4 0
False, because physical change does not involve the formation of substances. An example of physical change is change of state e.g water freezing .It is still water if you were to melt it.
Strike441 [17]3 years ago
3 0

Answer: The given statement is false.

Explanation:

Chemical change is defined as a change in which chemical composition and chemical properties of a substances changes.

For example: Rust formation on the iron.

Physical change is defined as a change in which form of the substance changes while chemical composition remains unchanged.

For example: Melting of an ice.

Here, new substance is formed which is different from the starting substance which means that a chemical change occurred.

You might be interested in
How many grams sodium bromide can be formed from 51 grams of sodium hydroxide?
raketka [301]

Explanation:

When working with moles only, you will start by applying stoichiometry to determine how the reactants will affect your amount of products in this reaction. For this question, we will assume that other reactants are in infinite qualities, so therefore, it is the amount of aluminum that we will be concerned with. You need to figure out how much aluminum is in the specified amount of aluminum bromide, and then how much aluminum hydroxide that will be able to create. Make sure all your units cancel out!

9.24 mol AlBr3 x (1 mol Al / 1 mol AlBr3) x (1 mol Al(OH)3 / 1 mol Al) = 9.24 mol AlBr3

When you're working with mole ratios that involve grams to moles conversions, the first thing you want to do is calculate the molecular weight of each component you are being asked about. Because the question was given to you as words instead of chemical formulas, you will want to figure out the chemical formulas. For example, aluminum hydroxide is Al(OH)3 and aluminum bromide is AlBr3. To calculate molecular weight, you will want to consult a periodic table, find the molecular weight for each atom, and then calculate the correct sum of each molecular weight. Make sure you keep track of the number of each atom you have, i.e. 3 oxygen and 3 hydrogen for aluminum hydroxide.

Na = 22.990 g/mol

O = 15.999 g/mol

H = 1.008 g/mol

NaOH = 22.990 g/mol + 15.999 g/mol + 1.008 g/mol = 39.997 g/mol

Al = 26.982 g/mol

O = 15.999 g/mol

H = 1.008 g/mol

Al(OH)3 = 26.982 g/mol + (3 x 15.999 g/mol) + (3 x 1.008 g/mol) = 78.003 g/mol

Now, if you begin with an amount of NaOH in grams, you will first have to convert that to moles in order to use the mole ratio.

24 g NaOH x (1 mol NaOH / 39.997 g NaOH) = 0.600 mol NaOH

Now, you will have to account for the part of the sodium hydroxide that will be present in the aluminum hydroxide. In this case, it is the hydroxide (OH) portion of the formula. There is one mole of OH in each mole of NaOH, but there are 3 moles of OH in each mole of Al(OH)3. You will start with the 0.600 mol NaOH you know you have and then use the mole ratio.

0.600 mol NaOH x (1 mol OH / 1 mol NaOH) x (1 mol Al(OH)3 / 3 mol OH) = 0.200 mol Al(OH)3

Finally, when you are converting from grams to grams, you will have to find the molecular weight of both the reactant and the product, convert reactants in grams to reactants in moles, then use the mole ratio, then convert the moles of product back to grams of product. This time, you are concerned about the mole ratio of sodium, as that is the element that is in both chemical formulas.

7 0
2 years ago
A horse runs 1 km in 15 s. What is the average speed
Reptile [31]

The average speed of the horse for the entire motion is 66.67 m/s.

The given parameters;

  • <em>distance traveled by the horse, d = 1 km = 1,000 m</em>
  • <em>time of motion of the horse, t = 15 s</em>

The average speed of the horse is calculated by dividing the total distance traveled by the horse by the time of motion.

The average speed of the horse is calculated as follows;

average\ speed = \frac{distance}{time} \\\\average\ speed =  \frac{1000 \ m}{15 \ s} = 66.67 \ m/s

Thus, the average speed of the horse for the entire motion is 66.67 m/s.

Learn more here: brainly.com/question/17289046

6 0
2 years ago
Solid mixture contains MgCl2 and NaCl. When 0.5000 g of this solid is dissolved in enough water to form 1.000 L of solution, the
aksik [14]

Answer:

83,40 (w/w) %

Explanation:

The osmotic pressure (π) is defined as:

π = iMRT

Where i is Van't Hoff factor (3 for MgCl₂ and 2 for NaCl), M is molarity, R is gas contant (0,082atmL/molK) and T is temperature (298,15K)

iM = π / RT

iM = 0,01607mol/L

It is possible to write:

<em>3x+2y = 0,01607mol/L </em><em>(1)</em>

Where x are moles of MgCl₂ and y moles of NaCl.

<em>-M = moles of each compund because M is molarity (moles/L) and there is 1,000L-</em>

Knowing molar mass of MgCl₂ is 95,2 g/mol and for NaCl is 58,44g/mol:

<em>x×95,211 + y×58,44 = 0,5000g </em><em>(2)</em>

Replacing (2) in (1):

3x+2(0,0086 - 1,629x) = 0,01607mol/L

-0,258x = -0,00113

<em>x = 0,004380 moles of MgCl₂</em>

In grams:

0,004380 moles of MgCl₂×(95,211g/mol) = 0,417g of MgCl₂

Mass percent is:

(0,4170g of MgCl₂/0,5000g of solid) ×100 = <em>83,40 (w/w) %</em>

I hope it helps!

4 0
3 years ago
a square boat made from iron has overall dimensions of 2.00 cm x 11.0 cm x 11.0 cm. it has a mass of 213 g. what is its density
Rus_ich [418]
Volume:

2.00 x 11.0 x 11.0 => 242 cm³

mass : 213 g

D = m / V

D = 213 / 242

D = 0.880 g/cm³

Answer B

hope this helps!
5 0
3 years ago
Read 2 more answers
Helpppp me plzz....
Dmitry_Shevchenko [17]

2.a) warm air is lighter than cold air so thats why it's warmer upstairs than downstairs
3.d) Conduction<span> is the process by which heat energy is transmitted through contact with neighboring molecules</span> 
4.d) the lamp radiates heat throughout the plants 
4 0
3 years ago
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