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3 years ago

What properties are associated with metals (grade 9 science)

Chemistry

1 answer:

quester [9]3 years ago

5 0

Answer:

metals can be magnetic.

Explanation:

certain types of metals are magnetic.

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What is true about water that is freezing?

Liono4ka [1.6K]

It is going through a physical change

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3 years ago

Read 2 more answers

How does the A Hreaction relate to the A He of molecules involved in a reaction?

igor_vitrenko [27]

Answer:

B. ΔHreaction = ΔH°f reactants- ΔH°f products

Explanation:

Using Hess's law, it is possible to sum ΔH of several related reactions to find ΔH of a particular reaction.

Having in mind Hess's law, ΔH°f is defined as the change in enthalpy during the formation of 1 mole of substance from its constituent elements (That is, pure elements, mono or diatomics, that have a ΔH° = 0).

For example, in ΔH°f of H₂O, the equation is:

H₂(g) + 1/2O₂(g) → H₂O(g)

The constituent elements with ΔH°f = 0 are H₂(g) and O₂(g).

Now, using Hess's law, you can sum the ΔH°f of substance in a reaction as, for example:

NaOH + HCl → H₂O + NaCl. ΔHr

The ΔH°f for each substance in the reaction is:

NaOH: Na + 1/2H₂ + 1/2O₂ → NaOH (1)

HCl: 1/2H₂ + 1/2Cl₂ → HCl (2)

H₂O: H₂ + 1/2O₂ → H₂O (3)

NaCl: Na + 1/2Cl₂ → NaCl (4)

The algebraic sum of (3) + (4) is -(ΔH°f reactants):

H₂ + 1/2O₂ + Na + 1/2Cl₂ → NaCl + H₂O ΔH°f reactants

This reaction - {(1)+(2)} ΔH°f products

NaOH + HCl → H₂O + NaCl.

ΔHr = ΔH°f reactants- ΔH°f products

In the example, we obtain this relationship that can be expanded for all reactions. Thus, right answer is:

<h3>B. ΔHreaction = ΔH°f reactants- ΔH°f products</h3>

8 0

3 years ago

A solution with a ph of 2.0 has a hydrogen ion concentration ten times greater than a solution with a ph

weqwewe [10]

The answer is c. 0.20 .

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3 years ago

_: brings food and water to your cells.

Rama09 [41]

Answer:

Mitochondria brings food and water to your cells

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3 years ago

When magnesium reacts with hydrochloric acid, hydrogen gas is formed: 2HCl + Mg → H2 + MgCl2. What is the volume of hydrogen pro

Maksim231197 [3]

Answer:- C. 16.4 L

Solution:- The given balanced equation is:

$2HCl+Mg\rightarrow H_2+MgCl_2$

From this equation, there is 2:1 mol ratio between HCl and hydrogen gas. First of all we calculate the moles of hydrogen gas from given grams of HCl using stoichiometry and then the volume of hydrogen gas could be calculated using ideal gas law equation, PV = nRT.

Molar mass of HCl = 1.008 + 35.45 = 36.458 gram per mol

The calculations are shown below:

$49.0gHCl(\frac{1molHCl}{36.458gHCl})(\frac{1molH_2}{2molHCl})$

= $0.672molH_2$

Now we will use ideal gas equation to calculate the volume.

n = 0.672 mol

T = 25 + 273 = 298 K

P = 101.3 kPa = 1 atm

R = $0.0821\frac{atm.L}{mol.K}$

PV = nRT

1(V) = (0.672)(0.0821)(298)

V = 16.4 L

From calculations, 16.4 L of hydrogen gas are formed and so the correct choice is C.

7 0

3 years ago