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3 years ago

The percent yield for a chemical reaction can not be calculated until the reaction is completed

Chemistry

1 answer:

maw [93]3 years ago

5 0

Answer:

False

Explanation:

using the measurements of the amounts of chemicals, it can be calculated to some degree of accuracy depending mainly on the accuracy of the measurements and enviroments of the reaction

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Strontium-90, a radioactive isotope with applications in medicine, has a half-life of approximately 30 years. Out of a 100-gram

AveGali [126]

There are 2 grams remain

<h3>Further explanation</h3>

Given

t1/2 = 30 years

t = 170 years

No = 100 g

Required

Remaining sample

Solution

General formulas used in decay:

$\large{\boxed{\bold{N_t=N_0(\dfrac{1}{2})^{t/t\frac{1}{2} }}}$

Input the value :

$\tt Nt=100.\dfrac{1}{2}^{170/30}\\\\Nt=1.969\approx 2~grams$

5 0

2 years ago

When 1.5 mol calcium nitrate dissolves in water, how many moles of ions should be present in solution?

____ [38]

Answer:

1.5 moles of Ca²⁺ and 3 moles of NO₃⁻

Explanation:

This is the dissociation:

Ca(NO₃)₂ → Ca²⁺ + 2NO₃⁻

1.5 moles of salt will have the same moles of ion Ca²⁺ and the double of moles, of nitrate according to the equation.

Therefore will be 1.5 moles of Ca²⁺ and 3 moles of NO₃⁻

5 0

2 years ago

The efficiency of the wedge is low because of _____.

Ket [755]

Answer:friction

Explanation:

6 0

3 years ago

Oxidation unit test

3241004551 [841]

In this case, according to the given information about the oxidation numbers anf the compounds given, it turns out possible to figure out the oxidation number of manganese in both MnI2, manganese (II) iodide and MnO2, manganese (IV) oxide, by using the concept of charge balance.

Thus, we can define the oxidation state of iodine and oxygen as -1 and -2, respectively, since the former needs one electron to complete the octet and the latter, two of them.

Next, we can write the following $x$ , since manganese has five oxidation states, and it is necessary to calculate the appropriate ones:

$Mn^xI_2^-\\\\Mn ^xO_2^{-2}$

Next, we multiply each anion's oxidation number by the subscript, to obtain the following:

$Mn^xI_2^-\rightarrow x-2=0;x=+2\\\\Mn ^xO_2^{-2}\rightarrow x-4=0;x=+4$

Thus, the correct choice is Manganese has an oxidation number of +2 in Mnl2 and +4 in MnO2.

Learn more:

8 0

2 years ago

Compared to other minerals, a mineral that is ranked higher on the mohs scale will be

Step2247 [10]

A mineral ranked higher in the mohs scale is relatively harder than other minerals. Mohs scale lists 10 minerals from the softest to hardest. The hardest mineral is diamon while the softest one is talc. The two minerals compared are scratched with each other. The scratched one is the softer mineral.

6 0

3 years ago