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4 years ago

What is the difference between melting and melting point

Chemistry

1 answer:

Yakvenalex [24]4 years ago

4 0

Answer:

Melting Is when a substance is actually melting and melting point is a point at which a substance is able to melt.

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Uranium-267 undergoes alpha decay, what is the mass of the new element?

Firlakuza [10]

Answer:

will this help ?

Explanation:

(108Hs) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 265Hs in 1984. There are 12 known isotopes from 263Hs to 277Hs and 1–4 isomers. The most stable isotope of hassium cannot be determined based on existing data due to uncertainty that arises from the low number of measurements. The confidence interval of half-life of 269Hs corresponding to one standard deviation (the interval is ~68.3% likely to contain the actual value) is 16 ± 6 seconds, whereas that of 270Hs is 9 ± 4 seconds. It is also possible that 277mHs is more stable than both of these, with its half-life likely being 110 ± 70 seconds, but only one event of decay of this isotope has been registered as of 2016.[1][2].

3 0

3 years ago

How many moles would you need to have 7.85 x 10^22 molecules of ammonia (NH3).

RSB [31]

<h3>Answer:</h3>

0.130 moles NH₃

<h3>General Formulas and Concepts:</h3>

<u>Pre-Algebra</u>

Order of Operations: BPEMDAS

Brackets
Parenthesis
Exponents
Multiplication
Division
Addition
Subtraction

Left to Right

<u>Chemistry</u>

<u>Atomic Structure</u>

Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.

<u>Stoichiometry</u>

Using Dimensional Analysis

<h3>Explanation:</h3>

<u>Step 1: Define</u>

[Given] 7.85 × 10²² molecules NH₃

[Solve] moles NH₃

<u>Step 2: Identify Conversions</u>

Avogadro's Number

<u>Step 3: Convert</u>

[DA] Set up: $\displaystyle 7.85 \cdot 10^{22} \ molecules \ NH_3(\frac{1 \ mol \ NH_3}{6.022 \cdot 10^{23} \ molecules \ NH_3})$
[DA] Multiply/Divide [Cancel out units]: $\displaystyle 0.130355 \ moles \ NH_3$

<u>Step 4: Check</u>

<em>Follow sig fig rules and round. We are given 3 sig figs.</em>

0.130355 moles NH₃ ≈ 0.130 moles NH₃

3 0

3 years ago

What would be the product if dimethyl maleate was heated in the presence of 3-sulfolene?

prisoha [69]

An organic reaction between a substituted alkene and a conjugated diene to form a substituted cyclohexene derivative is said to be Diels-Alder reaction (specifically, [4+2 cycloaddition). The formation of new $\sigma$ -bonds is the driving force of this reaction, which is energetically more stable than the $\pi$ -bonds.

The reaction that takes place due to the heating of dimethyl maleate in presence of 3-sulfolene is as shown in the image.

On heating 3-sulfolene the compound breaks down to give sulfur dioxide gas and butadiene. This diene then reacts with dimethyl maleate which acts as a dienophiles and then these two diene and dienophiles will undergo a Diels-Alder reaction to form a new 6-membered cyclohexene ring.

Thus, the product formed due to the heating of dimethyl maleate in presence of 3-sulfolene is dimethyl cyclohex-4-ene-1,2-dicarboxylate.

7 0

3 years ago

What is the percent by weight of sodium in sodium sulfate (Na2SO4)? (The molar mass of Na = 22.99, S = 32.07, and O = 16.00.) 16

34kurt

The total mass would be 142.05 g/mol. Since sodium is 22.99 g/mol and there are 2 sodium atoms, it would be 45.98 g/mol. Divide 45.98 by 142.05 and you get 32.37%

8 0

4 years ago

Read 2 more answers

How many molecules of ascorbic acid (vitamin c, c6h8o6) are in a 500 mg tablet?

Elden [556K]

1) molar mass of the C6H8O<span>6, you need to consult the atomic weight of the C, H and O atoms that are in the periodic table: C is 12; H is 1; O is 16
(12x6)+(1x8)+(16x6)= 176g/mol

</span><span>176 g = 1 mol
0,5 g = x mol 500mg= 0,5 grams

molar mass = mass÷ moles
176 = 0,5÷ x
x= 2,84 x 10⁻³ mol

2) To find the number of molecules present in those </span>2,84 x 10⁻³ mol we need to multiple the moles by the <span>Avogadro's constant
No. of molecules = Avogadro's constant x n° of moles
</span>No. of molecules = 6.022 x 10²³ x 2,84 x 10⁻³ <span>
= 1.71 x 10²¹ molecules of vit C. </span>

6 0

3 years ago

Read 2 more answers