All categories

3 years ago

Which process is a physical change? iron rusting milk turning into curd water boiling paper burning hard water stains pipes?

Chemistry

2 answers:

Elodia [21]3 years ago

6 0

Iron rusting over is a physical change.

Len [333]3 years ago

5 0

Answer: Option (c) is the correct answer.

Explanation:

A change that causes no change in chemical composition of a substance is known as a physical change.

For example, boiling of water is a physical change as state of water is changing from liquid to vapors.

On the other hand, a change that causes a change in chemical composition of a substance is known as a chemical change.

For example, rusting of iron, churning of milk into curd, burning of paper, stains of hard water on pipes are all chemical changes.

Thus, we can conclude that water boiling process is a physical change.

You might be interested in

The following data was collected for the formation of ammonia (NH3) based on the following overall reaction: N2 + 3H2 = 2NH3 N2

notsponge [240]

Answer : The unit for the rate constant in the rate law for the formation of ammonia is, $M^{-2}min^{-1}$

Explanation :

Rate law is defined as the expression which expresses the rate of the reaction in terms of molar concentration of the reactants with each term raised to the power their stoichiometric coefficient of that reactant in the balanced chemical equation.

For the given chemical equation:

$N_2+3H_2\rightarrow 2NH_3$

Rate law expression for the reaction:

$\text{Rate}=k[N_2]^a[H_2]^b$

where,

a = order with respect to $N_2$

b = order with respect to $H_2$

Expression for rate law for first observation:

$0.0021=k(0.10)^a(0.10)^b$ ....(1)

Expression for rate law for second observation:

$0.0084=k(0.10)^a(0.20)^b$ ....(2)

Expression for rate law for third observation:

$0.0672=k(0.20)^a(0.40)^b$ ....(3)

Dividing 2 by 1, we get:

$\frac{0.0084}{0.0021}=\frac{k(0.10)^a(0.20)^b}{k(0.10)^a(0.10)^b}\\\\4=2^b\\b=2$

Dividing 3 by 1 and also put value of b, we get:

$\frac{0.0672}{0.0021}=\frac{k(0.20)^a(0.40)^2}{k(0.10)^a(0.10)^2}\\\\2=2^a\\a=1$

Thus, the rate law becomes:

$\text{Rate}=k[N_2]^a[H_2]^b$

$\text{Rate}=k[N_2]^1[H_2]^2$

Now, calculating the value of 'k' by using any expression.

$0.0021=k(0.10)^1(0.10)^2$

$k=2.1M^{-2}min^{-1}$

The value of the rate constant 'k' for this reaction is $2.1M^{-2}min^{-1}$

That means, the unit for the rate constant in the rate law for the formation of ammonia is, $M^{-2}min^{-1}$

7 0

4 years ago

What is the theoretical yield of vanadium, in moles, that can be produced by the reaction of 1.0 mole of V2O5 with 4.0 moles of

IRINA_888 [86]

Answer:

Theoretical yield of vanadium = 1.6 moles

Explanation:

Moles of $V_2O_5$ = 1.0 moles

Moles of $Ca$ = 4.0 moles

According to the given reaction:-

$V_2O_5_{(s)} + 5Ca_{(l)}\rightarrow 2V_{(l)} + 5CaO_{(s)}$

1 mole of $V_2O_5$ react with 5 moles of $Ca$

Moles of Ca available = 4.0 moles

Limiting reagent is the one which is present in small amount. Thus, Ca is limiting reagent. (4.0 < 5)

The formation of the product is governed by the limiting reagent. So,

5 moles of Ca on reaction forms 2 moles of V

1 mole of Ca on reaction for 2/5 mole of V

4.0 mole of Ca on reaction for $\frac{2}{5}\times 4$ mole of V

Moles of V = 1.6 moles

Theoretical yield of vanadium = 1.6 moles

4 0

3 years ago

What do we need to know about a molecule in order to carry out molarity calculations

professor190 [17]

Answer the type of cell

Explanation:

7 0

3 years ago

suppose you need to build a raft to cross a fast-moving river. describe the physical and chemical properties of the raft that wo

amid [387]

You need a density less than water enough strength not to bend or break

8 0

3 years ago

What is a possible quantum number set for an electron in the 3s orbital of a magnesium atom

Alik [6]

n = 3
l = 0
$m_l$ = 0

$m_s$ = 1/2 or -1/2

<h3>Explanation</h3>

There are four quantum numbers in an electron that orbits the atom.

n, the principal quantum number.
l, the angular quantum number.
$m_l$ , the magnetic quantum number.
$m_s$ , the spin quantum number.

n is a positive integer. The value of n indicates the main shell of the electron. The electron in question is in the 3s orbital. As a result, n = 3.

l is a non-negative integer. The value of l indicates the type of subshell ("orbital") of the electron. The types of subshells possible depends on the main shell. For example, both s and p orbitals exist in the second main shell. However, only the s orbital exists in the first main shell. The value of l ranges from 0 to n - 1.

l = 0 indicates an s orbital.
l = 1 indicates a p orbital.
l = 2 indicates a d orbital.
l = 3 indicates an f orbital.

The electron in question is in an s orbital. As a result, l = 0.

$m_l$ is an integer. The value of $m_l$ indicates the position of the electron within the subshell. The range of $m_l$ depends on the value of l. $m_l$ ranges from -l to l (that's -l, ..., -1, 0, 1, ... l). Accordingly, there are 2 l + 1 orbitals in a l subshell. l = 0 for this 3s electron. There's only one orbital in the 3s subshell. The only $m_l$ value possible for this electron is 0.

The value of $m_s$ is either - 1/2 or 1/2. It indicates the position of an electron within a single orbital. The value of $m_s$ does not depend on that of n, l, or $m_l$ . However, by the Pauli Exclusion Principle, at least one of the four numbers must differ for two electrons in the same atom. In case all three of n, l, and $m_l$ are the same, the two electrons must differ in $m_s$ . However, this question asks only for the number of one single electron. Thus, giving either - 1/2 or 1/2 shall work.

<h3>Reference</h3>

Vitz et. al, "5.8 Quantum Numbers (Electronic)", ChemPRIME (Moore et al.), Chemistry Libretexts. 27 Oct 2017.

7 0

4 years ago