What is the kinetic energy of a ball with a mass of 0.5 kg and a velocity of 10 m/s? (Formula:) 25 J 5 J 50 J 100 JWhat is the k
2 answers:
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Answer:
Explanation:
We are asked to find the mass of a number of platinum (Pt) atoms.
<h3>1. Convert Atoms to Moles </h3>First, we convert atoms to moles using Avogadro's Number or 6.022 × 10²³. This is the number of particles (atoms, molecules, formula units, etc.) in 1 mole of a substance. In this case, the particles are platinum atoms.
We will convert using dimensional analysis so we set up a ratio using the information we know (6.022 × 10²³ platinum atoms in 1 mole of platinum).
We are converting 4.99 ×10²¹ atoms of Pt to moles of Pt, so we multiply by this value.
Flip the ratio so the units of atoms of platinum cancel.
Divide.
Next, we convert moles to grams using the molar mass. This is the mass of 1 mole of a substance. This is found on the Periodic Table because it is equivalent to the atomic mass, but the units are grams per mole instead of atomic mass units. Look up platinum's molar mass.
- Pt: 195.08 g/mol
Set up another ratio using this new information (195.08 grams of Pt in 1 mole of Pt).
Multiply by the number of moles we just calculated.
The units of moles of platinum cancel.
The original measurement of atoms ( 4.99 ×10²¹ ) has 3 significant figures, so our answer must have the same. For the number we found, that is the hundredth place. The 6 in the thousandth place tells us to round the 1 up to a 2.
There are approximately <u>1.62 grams of platinum</u> in 4.99 ×10²¹ atoms of platinum.
Answer:
See below
Step-by-step explanation:
(a) Shape
The formula for water is H-O-H.
The central O atom has four electron pairs around it. They try to get as far from each other as possible, so they point toward the corners of a tetrahedron.
Only two of the pairs have a hydrogen atom attached, so water has a bent shape. The H-O-H bond angle is about 104°.
(b) Chemical magnet
The O atom has a greater attraction than H for the shared electrons in the O-H bonds, so the electrons spend more time near the O.
This gives the O atom a partial negative charge (pink in the diagram) and the H atoms a partial positive charge (blue).
The water molecule acts like a chemical magnet because its negative end attracts the positive ends of other molecules, while its positive ends attract the negative ends of other molecules.
